Mehdi AMINI via llvm-dev
2017-Jun-19 16:34 UTC
[llvm-dev] LLVM behavior different depending on function symbol name
using `opt --print-after-all -O3` I see that EarlyCSE is interpreting the
call to `ceil` and constant fold:
*** IR Dump After Early CSE ***
; Function Attrs: nobuiltin nounwind
define i1 @do_test() #2 {
Entry:
%0 = call fastcc float @ceil(float 0.000000e+00) #6
%1 = call fastcc float @ceil32(float 0.000000e+00) #6
%2 = fcmp fast oeq float 0.000000e+00, %1
ret i1 %2
}
So just running `opt -early-cse -debug` seems enough:
EarlyCSE Simplify: %0 = call fastcc float @ceil(float 0.000000e+00) #6
to: float 0.000000e+00
I suspect it is not correct from EarlyCSE to do that.
--
Mehdi
2017-06-19 9:27 GMT-07:00 Andrew Kelley <superjoe30 at gmail.com>:
> Oops. Pressed send on accident.
>
> With -O3, the module gets rewritten to:
> ; Function Attrs: nobuiltin nounwind
> define i1 @do_test() local_unnamed_addr #0 !dbg !16 {
> Entry:
> %x.sroa.0.i.i = alloca i32, align 4
> %x.sroa.0.i.i.i = alloca i32, align 4
> tail call void @llvm.dbg.value(metadata float 0.000000e+00, i64 0,
> metadata !21, metadata !28) #3, !dbg !29
> tail call void @llvm.dbg.value(metadata float 0.000000e+00, i64 0,
> metadata !32, metadata !28) #3, !dbg !44
> tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !35,
> metadata !28) #3, !dbg !49
> tail call void @llvm.dbg.value(metadata i32 -127, i64 0, metadata !39,
> metadata !28) #3, !dbg !50
> %x.sroa.0.i.i.i.0.sroa_cast = bitcast i32* %x.sroa.0.i.i.i to i8*, !dbg
> !51
> call void @llvm.lifetime.start(i64 4, i8* nonnull
> %x.sroa.0.i.i.i.0.sroa_cast), !dbg !51
> tail call void @llvm.dbg.value(metadata float 0.000000e+00, i64 0,
> metadata !57, metadata !28) #3, !dbg !51
> tail call void @llvm.dbg.value(metadata float* undef, i64 0, metadata
> !61, metadata !28) #3, !dbg !67
>
%x.sroa.0.i.i.i.0.x.sroa.0.i.i.0.x.sroa.0.i.0.x.sroa.0.0.x.sroa.0.0.x.0.1.i.i.i
> = load i32, i32* %x.sroa.0.i.i.i, align 4, !dbg !68
> store volatile i32 %x.sroa.0.i.i.i.0.x.sroa.0.i.
> i.0.x.sroa.0.i.0.x.sroa.0.0.x.sroa.0.0.x.0.1.i.i.i, i32* %x.sroa.0.i.i.i,
> align 4, !dbg !70
> call void @llvm.lifetime.end(i64 4, i8* nonnull
> %x.sroa.0.i.i.i.0.sroa_cast), !dbg !71
> tail call void @llvm.dbg.value(metadata float 0.000000e+00, i64 0,
> metadata !32, metadata !28) #3, !dbg !72
> tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !35,
> metadata !28) #3, !dbg !75
> tail call void @llvm.dbg.value(metadata i32 -127, i64 0, metadata !39,
> metadata !28) #3, !dbg !76
> %x.sroa.0.i.i.0.sroa_cast = bitcast i32* %x.sroa.0.i.i to i8*, !dbg !77
> call void @llvm.lifetime.start(i64 4, i8* nonnull
> %x.sroa.0.i.i.0.sroa_cast), !dbg !77
> tail call void @llvm.dbg.value(metadata float 0.000000e+00, i64 0,
> metadata !57, metadata !28) #3, !dbg !77
> tail call void @llvm.dbg.value(metadata float* undef, i64 0, metadata
> !61, metadata !28) #3, !dbg !79
> %x.sroa.0.i.i.0.x.sroa.0.i.0.x.sroa.0.0.x.sroa.0.0.x.0.1.i.i = load
> i32, i32* %x.sroa.0.i.i, align 4, !dbg !80
> store volatile i32 %x.sroa.0.i.i.0.x.sroa.0.i.0.
> x.sroa.0.0.x.sroa.0.0.x.0.1.i.i, i32* %x.sroa.0.i.i, align 4, !dbg !81
> call void @llvm.lifetime.end(i64 4, i8* nonnull
> %x.sroa.0.i.i.0.sroa_cast), !dbg !82
> ret i1 false, !dbg !83
> }
>
>
> Note the `ret i1 false` at the end. Expected it to return true.
>
>
> On Mon, Jun 19, 2017 at 12:26 PM, Andrew Kelley <superjoe30 at
gmail.com>
> wrote:
>
>>
>>
>> On Mon, Jun 19, 2017 at 12:06 PM, Mehdi AMINI <joker.eph at
gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> 2017-06-19 8:45 GMT-07:00 Andrew Kelley via llvm-dev <
>>> llvm-dev at lists.llvm.org>:
>>>
>>>> Greetings,
>>>>
>>>> I have a Zig implementation of ceil which is emitted into LLVM
IR like
>>>> this:
>>>>
>>>> ; Function Attrs: nobuiltin nounwind
>>>> define internal fastcc float @ceil(float) unnamed_addr #3 !dbg
!644 {
>>>> Entry:
>>>> %x = alloca float, align 4
>>>> store float %0, float* %x
>>>> call void @llvm.dbg.declare(metadata float* %x, metadata
!649,
>>>> metadata !494), !dbg !651
>>>> %1 = load float, float* %x, !dbg !652
>>>> %2 = call fastcc float @ceil32(float %1) #8, !dbg !656
>>>> ret float %2, !dbg !657
>>>> }
>>>>
>>>> Test case:
>>>>
>>>> test "math.ceil" {
>>>> assert(ceil(f32(0.0)) == ceil32(0.0));
>>>> assert(ceil(f64(0.0)) == ceil64(0.0));
>>>> }
>>>>
>>>>
>>>> When I compile with optimizations on, this test case fails. The
>>>> optimized code for the test case ends up being a call to panic
(assertion
>>>> failure), which means that LLVM determined the test failed at
compile-time.
>>>>
>>>> What's strange about this is that if I change the function
name from
>>>> @ceil to @ceil_asdf (and change the callers) then the test
passes.
>>>>
>>>> So I think LLVM is doing some kind of string comparison on the
symbol
>>>> name and detecting that it is "ceil" and then having
different, undesired
>>>> behavior.
>>>>
>>>> I tried putting `nobuiltin` in the function attributes and at
the
>>>> callsite, but that did not change anything.
>>>>
>>>> Any ideas what's going on?
>>>>
>>>
>>> I think it'd be a lot easier to figure if you provide a
standalone repro.
>>>
>>
>> Standalone repro:
>>
>> ; ModuleID = 'test'
>> source_filename = "test"
>> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>> target triple = "x86_64-unknown-linux-gnu"
>>
>> %"[]u8" = type { i8*, i64 }
>>
>> @__zig_panic_implementation_provided = internal unnamed_addr constant
i1
>> true, align 1
>>
>> ; Function Attrs: nounwind
>> declare void @llvm.debugtrap() #0
>>
>> ; Function Attrs: argmemonly nounwind
>> declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8*
>> nocapture readonly, i64, i32, i1) #1
>>
>> ; Function Attrs: argmemonly nounwind
>> declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64,
i32,
>> i1) #1
>>
>> ; Function Attrs: nobuiltin nounwind
>> define i1 @do_test() #2 !dbg !16 {
>> Entry:
>> %0 = call fastcc float @ceil(float 0.000000e+00) #6, !dbg !21
>> %1 = call fastcc float @ceil32(float 0.000000e+00) #6, !dbg !23
>> %2 = fcmp fast oeq float %0, %1, !dbg !24
>> ret i1 %2, !dbg !25
>> }
>>
>> ; Function Attrs: cold nobuiltin noreturn nounwind
>> define linkonce coldcc void @__zig_panic(i8* nonnull readonly, i64) #3
>> !dbg !26 {
>> Entry:
>> %2 = alloca %"[]u8", align 8
>> %message_ptr = alloca i8*, align 8
>> %message_len = alloca i64, align 8
>> store i8* %0, i8** %message_ptr
>> call void @llvm.dbg.declare(metadata i8** %message_ptr, metadata !34,
>> metadata !37), !dbg !38
>> store i64 %1, i64* %message_len
>> call void @llvm.dbg.declare(metadata i64* %message_len, metadata !35,
>> metadata !37), !dbg !39
>> %3 = load i64, i64* %message_len, !dbg !40
>> %4 = load i8*, i8** %message_ptr, !dbg !44
>> %5 = getelementptr inbounds %"[]u8", %"[]u8"* %2,
i32 0, i32 0, !dbg !44
>> %6 = getelementptr inbounds i8, i8* %4, i64 0, !dbg !44
>> store i8* %6, i8** %5, !dbg !44
>> %7 = getelementptr inbounds %"[]u8", %"[]u8"* %2,
i32 0, i32 1, !dbg !44
>> %8 = sub nsw i64 %3, 0, !dbg !44
>> store i64 %8, i64* %7, !dbg !44
>> call fastcc void @panic(%"[]u8"* byval %2) #6, !dbg !45
>> unreachable, !dbg !45
>> }
>>
>> ; Function Attrs: nobuiltin nounwind
>> define internal fastcc float @ceil(float) unnamed_addr #2 !dbg !46 {
>> Entry:
>> %x = alloca float, align 4
>> store float %0, float* %x
>> call void @llvm.dbg.declare(metadata float* %x, metadata !51,
metadata
>> !37), !dbg !53
>> %1 = load float, float* %x, !dbg !54
>> %2 = call fastcc float @ceil32(float %1) #7, !dbg !58
>> ret float %2, !dbg !59
>> }
>>
>> ; Function Attrs: nobuiltin nounwind
>> define internal fastcc float @ceil32(float) unnamed_addr #2 !dbg !60 {
>> Entry:
>> %x = alloca float, align 4
>> %u = alloca i32, align 4
>> %e = alloca i32, align 4
>> %m = alloca i32, align 4
>> store float %0, float* %x
>> call void @llvm.dbg.declare(metadata float* %x, metadata !62,
metadata
>> !37), !dbg !72
>> %1 = load float, float* %x, !dbg !73
>> %2 = bitcast float %1 to i32, !dbg !74
>> store i32 %2, i32* %u, !dbg !75
>> call void @llvm.dbg.declare(metadata i32* %u, metadata !63, metadata
>> !37), !dbg !75
>> %3 = load i32, i32* %u, !dbg !76
>> %4 = lshr i32 %3, 23, !dbg !77
>> %5 = and i32 %4, 255, !dbg !78
>> %6 = sub nsw i32 %5, 127, !dbg !79
>> store i32 %6, i32* %e, !dbg !80
>> call void @llvm.dbg.declare(metadata i32* %e, metadata !67, metadata
>> !37), !dbg !80
>> call void @llvm.dbg.declare(metadata i32* %m, metadata !70, metadata
>> !37), !dbg !81
>> %7 = load i32, i32* %e, !dbg !82
>> %8 = icmp sge i32 %7, 23, !dbg !84
>> br i1 %8, label %Then, label %Else, !dbg !84
>>
>> Then: ; preds = %Entry
>> %9 = load float, float* %x, !dbg !85
>> ret float %9, !dbg !87
>>
>> Else: ; preds = %Entry
>> %10 = load i32, i32* %e, !dbg !88
>> %11 = icmp sge i32 %10, 0, !dbg !89
>> br i1 %11, label %Then1, label %Else2, !dbg !89
>>
>> Then1: ; preds = %Else
>> %12 = load i32, i32* %e, !dbg !90
>> %13 = lshr i32 8388607, %12, !dbg !92
>> store i32 %13, i32* %m, !dbg !93
>> %14 = load i32, i32* %u, !dbg !94
>> %15 = load i32, i32* %m, !dbg !95
>> %16 = and i32 %14, %15, !dbg !96
>> %17 = icmp eq i32 %16, 0, !dbg !97
>> br i1 %17, label %Then3, label %Else4, !dbg !97
>>
>> Else2: ; preds = %Else
>> %18 = load float, float* %x, !dbg !98
>> %19 = fadd fast float %18, 0x4770000000000000, !dbg !100
>> call fastcc void @forceEval(float %19) #6, !dbg !101
>> %20 = load i32, i32* %u, !dbg !102
>> %21 = lshr i32 %20, 31, !dbg !103
>> %22 = icmp ne i32 %21, 0, !dbg !104
>> br i1 %22, label %Then5, label %Else6, !dbg !104
>>
>> Then3: ; preds = %Then1
>> %23 = load float, float* %x, !dbg !105
>> ret float %23, !dbg !107
>>
>> Else4: ; preds = %Then1
>> br label %EndIf, !dbg !108
>>
>> Then5: ; preds = %Else2
>> ret float -0.000000e+00, !dbg !109
>>
>> Else6: ; preds = %Else2
>> br label %EndIf7, !dbg !111
>>
>> EndIf: ; preds = %Else4
>> %24 = load float, float* %x, !dbg !112
>> %25 = fadd fast float %24, 0x4770000000000000, !dbg !113
>> call fastcc void @forceEval(float %25) #6, !dbg !114
>> %26 = load i32, i32* %u, !dbg !115
>> %27 = lshr i32 %26, 31, !dbg !116
>> %28 = icmp eq i32 %27, 0, !dbg !117
>> br i1 %28, label %Then8, label %Else9, !dbg !117
>>
>> EndIf7: ; preds = %Else6
>> br label %EndIf11, !dbg !118
>>
>> Then8: ; preds = %EndIf
>> %29 = load i32, i32* %u, !dbg !119
>> %30 = load i32, i32* %m, !dbg !121
>> %31 = add nuw i32 %29, %30, !dbg !122
>> store i32 %31, i32* %u, !dbg !122
>> br label %EndIf10, !dbg !123
>>
>> Else9: ; preds = %EndIf
>> br label %EndIf10, !dbg !123
>>
>> EndIf10: ; preds = %Else9,
%Then8
>> %32 = load i32, i32* %u, !dbg !124
>> %33 = load i32, i32* %m, !dbg !125
>> %34 = xor i32 %33, -1, !dbg !126
>> %35 = and i32 %32, %34, !dbg !127
>> store i32 %35, i32* %u, !dbg !127
>> %36 = load i32, i32* %u, !dbg !128
>> %37 = bitcast i32 %36 to float, !dbg !129
>> br label %EndIf11, !dbg !118
>>
>> EndIf11: ; preds = %EndIf10,
>> %EndIf7
>> %38 = phi float [ %37, %EndIf10 ], [ 1.000000e+00, %EndIf7 ], !dbg
!118
>> ret float %38, !dbg !130
>> }
>>
>> ; Function Attrs: nobuiltin noreturn nounwind
>> define internal fastcc void @panic(%"[]u8"* byval nonnull
readonly)
>> unnamed_addr #4 !dbg !131 {
>> Entry:
>> call void @llvm.dbg.declare(metadata %"[]u8"* %0, metadata
!141,
>> metadata !37), !dbg !142
>> call void @llvm.debugtrap(), !dbg !143
>> br label %WhileCond, !dbg !146
>>
>> WhileCond: ; preds = %WhileCond,
>> %Entry
>> br label %WhileCond, !dbg !146
>> }
>>
>> ; Function Attrs: nobuiltin nounwind
>> define internal fastcc void @forceEval(float) unnamed_addr #2 !dbg !147
{
>> Entry:
>> %value = alloca float, align 4
>> %x = alloca float, align 4
>> %p = alloca float*, align 8
>> store float %0, float* %value
>> call void @llvm.dbg.declare(metadata float* %value, metadata !151,
>> metadata !37), !dbg !158
>> call void @llvm.dbg.declare(metadata float* %x, metadata !152,
metadata
>> !37), !dbg !159
>> store float* %x, float** %p, !dbg !160
>> call void @llvm.dbg.declare(metadata float** %p, metadata !155,
>> metadata !37), !dbg !160
>> %1 = load float*, float** %p, !dbg !161
>> %2 = load float, float* %x, !dbg !163
>> store volatile float %2, float* %1, !dbg !164
>> ret void, !dbg !165
>> }
>>
>> ; Function Attrs: nounwind readnone
>> declare void @llvm.dbg.declare(metadata, metadata, metadata) #5
>>
>> attributes #0 = { nounwind }
>> attributes #1 = { argmemonly nounwind }
>> attributes #2 = { nobuiltin nounwind }
>> attributes #3 = { cold nobuiltin noreturn nounwind }
>> attributes #4 = { nobuiltin noreturn nounwind }
>> attributes #5 = { nounwind readnone }
>> attributes #6 = { nobuiltin }
>> attributes #7 = { alwaysinline nobuiltin }
>>
>> !llvm.module.flags = !{!0}
>> !llvm.dbg.cu = !{!1}
>>
>> !0 = !{i32 2, !"Debug Info Version", i32 3}
>> !1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, producer:
>> "zig 0.0.0", isOptimized: true, runtimeVersion: 0,
emissionKind: FullDebug,
>> enums: !3, globals: !12)
>> !2 = !DIFile(filename: "test", directory: ".")
>> !3 = !{!4}
>> !4 = !DICompositeType(tag: DW_TAG_enumeration_type, name:
>> "GlobalLinkage", scope: !5, file: !5, line: 126, baseType:
!6, size: 8,
>> align: 8, elements: !7)
>> !5 = !DIFile(filename: "builtin.zig", directory:
>> "/home/andy/dev/zig/build/zig-cache")
>> !6 = !DIBasicType(name: "u8", size: 8, encoding:
DW_ATE_unsigned_char)
>> !7 = !{!8, !9, !10, !11}
>> !8 = !DIEnumerator(name: "Internal", value: 0)
>> !9 = !DIEnumerator(name: "Strong", value: 1)
>> !10 = !DIEnumerator(name: "Weak", value: 2)
>> !11 = !DIEnumerator(name: "LinkOnce", value: 3)
>> !12 = !{!13}
>> !13 = !DIGlobalVariableExpression(var: !14)
>> !14 = distinct !DIGlobalVariable(name:
"__zig_panic_implementation_provided",
>> linkageName: "__zig_panic_implementation_provided", scope:
!5, file: !5,
>> line: 189, type: !15, isLocal: true, isDefinition: true)
>> !15 = !DIBasicType(name: "bool", size: 8, encoding:
DW_ATE_boolean)
>> !16 = distinct !DISubprogram(name: "do_test", scope: !17,
file: !17,
>> line: 46, type: !18, isLocal: false, isDefinition: true, scopeLine: 46,
>> isOptimized: true, unit: !1, variables: !20)
>> !17 = !DIFile(filename: "test.zig", directory:
"/home/andy/dev/zig/build")
>> !18 = !DISubroutineType(types: !19)
>> !19 = !{!15}
>> !20 = !{}
>> !21 = !DILocation(line: 47, column: 16, scope: !22)
>> !22 = distinct !DILexicalBlock(scope: !16, file: !17, line: 46, column:
>> 29)
>> !23 = !DILocation(line: 47, column: 36, scope: !22)
>> !24 = !DILocation(line: 47, column: 27, scope: !22)
>> !25 = !DILocation(line: 47, column: 5, scope: !22)
>> !26 = distinct !DISubprogram(name: "__zig_panic", scope: !27,
file: !27,
>> line: 7, type: !28, isLocal: false, isDefinition: true, scopeLine: 7,
>> isOptimized: true, unit: !1, variables: !33)
>> !27 = !DIFile(filename: "zigrt.zig", directory:
>> "/home/andy/dev/zig/build/lib/zig/std/special")
>> !28 = !DISubroutineType(types: !29)
>> !29 = !{!30, !31, !32}
>> !30 = !DIBasicType(name: "void", encoding: DW_ATE_unsigned)
>> !31 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&const
u8",
>> baseType: !6, size: 64, align: 64)
>> !32 = !DIBasicType(name: "usize", size: 64, encoding:
DW_ATE_unsigned)
>> !33 = !{!34, !35}
>> !34 = !DILocalVariable(name: "message_ptr", arg: 1, scope:
!26, file:
>> !27, line: 7, type: !31)
>> !35 = !DILocalVariable(name: "message_len", arg: 2, scope:
!36, file:
>> !27, line: 7, type: !32)
>> !36 = distinct !DILexicalBlock(scope: !26, file: !27, line: 7, column:
30)
>> !37 = !DIExpression()
>> !38 = !DILocation(line: 7, column: 30, scope: !26)
>> !39 = !DILocation(line: 7, column: 54, scope: !36)
>> !40 = !DILocation(line: 12, column: 48, scope: !41)
>> !41 = distinct !DILexicalBlock(scope: !42, file: !27, line: 11, column:
>> 54)
>> !42 = distinct !DILexicalBlock(scope: !43, file: !27, line: 7, column:
86)
>> !43 = distinct !DILexicalBlock(scope: !36, file: !27, line: 7, column:
54)
>> !44 = !DILocation(line: 12, column: 43, scope: !41)
>> !45 = !DILocation(line: 12, column: 31, scope: !41)
>> !46 = distinct !DISubprogram(name: "ceil", scope: !17, file:
!17, line:
>> 3, type: !47, isLocal: true, isDefinition: true, scopeLine: 3,
isOptimized:
>> true, unit: !1, variables: !50)
>> !47 = !DISubroutineType(types: !48)
>> !48 = !{!49, !49}
>> !49 = !DIBasicType(name: "f32", size: 32, encoding:
DW_ATE_float)
>> !50 = !{!51}
>> !51 = !DILocalVariable(name: "x", arg: 1, scope: !52, file:
!17, line: 3,
>> type: !49)
>> !52 = distinct !DILexicalBlock(scope: !46, file: !17, line: 3, column:
13)
>> !53 = !DILocation(line: 3, column: 13, scope: !52)
>> !54 = !DILocation(line: 6, column: 36, scope: !55)
>> !55 = distinct !DILexicalBlock(scope: !56, file: !17, line: 4, column:
5)
>> !56 = distinct !DILexicalBlock(scope: !57, file: !17, line: 3, column:
35)
>> !57 = distinct !DILexicalBlock(scope: !52, file: !17, line: 3, column:
13)
>> !58 = !DILocation(line: 6, column: 16, scope: !55)
>> !59 = !DILocation(line: 5, column: 5, scope: !57)
>> !60 = distinct !DISubprogram(name: "ceil32", scope: !17,
file: !17, line:
>> 11, type: !47, isLocal: true, isDefinition: true, scopeLine: 11,
>> isOptimized: true, unit: !1, variables: !61)
>> !61 = !{!62, !63, !67, !70}
>> !62 = !DILocalVariable(name: "x", arg: 1, scope: !60, file:
!17, line:
>> 11, type: !49)
>> !63 = !DILocalVariable(name: "u", scope: !64, file: !17,
line: 12, type:
>> !66)
>> !64 = distinct !DILexicalBlock(scope: !65, file: !17, line: 11, column:
>> 26)
>> !65 = distinct !DILexicalBlock(scope: !60, file: !17, line: 11, column:
>> 11)
>> !66 = !DIBasicType(name: "u32", size: 32, encoding:
DW_ATE_unsigned)
>> !67 = !DILocalVariable(name: "e", scope: !68, file: !17,
line: 13, type:
>> !69)
>> !68 = distinct !DILexicalBlock(scope: !64, file: !17, line: 12, column:
5)
>> !69 = !DIBasicType(name: "i32", size: 32, encoding:
DW_ATE_signed)
>> !70 = !DILocalVariable(name: "m", scope: !71, file: !17,
line: 14, type:
>> !66)
>> !71 = distinct !DILexicalBlock(scope: !68, file: !17, line: 13, column:
5)
>> !72 = !DILocation(line: 11, column: 11, scope: !60)
>> !73 = !DILocation(line: 12, column: 27, scope: !64)
>> !74 = !DILocation(line: 12, column: 13, scope: !64)
>> !75 = !DILocation(line: 12, column: 5, scope: !64)
>> !76 = !DILocation(line: 13, column: 18, scope: !68)
>> !77 = !DILocation(line: 13, column: 20, scope: !68)
>> !78 = !DILocation(line: 13, column: 27, scope: !68)
>> !79 = !DILocation(line: 13, column: 35, scope: !68)
>> !80 = !DILocation(line: 13, column: 5, scope: !68)
>> !81 = !DILocation(line: 14, column: 5, scope: !71)
>> !82 = !DILocation(line: 16, column: 9, scope: !83)
>> !83 = distinct !DILexicalBlock(scope: !71, file: !17, line: 14, column:
5)
>> !84 = !DILocation(line: 16, column: 11, scope: !83)
>> !85 = !DILocation(line: 17, column: 16, scope: !86)
>> !86 = distinct !DILexicalBlock(scope: !83, file: !17, line: 16, column:
>> 18)
>> !87 = !DILocation(line: 17, column: 9, scope: !86)
>> !88 = !DILocation(line: 19, column: 14, scope: !83)
>> !89 = !DILocation(line: 19, column: 16, scope: !83)
>> !90 = !DILocation(line: 20, column: 31, scope: !91)
>> !91 = distinct !DILexicalBlock(scope: !83, file: !17, line: 19, column:
>> 22)
>> !92 = !DILocation(line: 20, column: 24, scope: !91)
>> !93 = !DILocation(line: 20, column: 11, scope: !91)
>> !94 = !DILocation(line: 21, column: 13, scope: !91)
>> !95 = !DILocation(line: 21, column: 17, scope: !91)
>> !96 = !DILocation(line: 21, column: 15, scope: !91)
>> !97 = !DILocation(line: 21, column: 19, scope: !91)
>> !98 = !DILocation(line: 31, column: 19, scope: !99)
>> !99 = distinct !DILexicalBlock(scope: !83, file: !17, line: 30, column:
>> 12)
>> !100 = !DILocation(line: 31, column: 21, scope: !99)
>> !101 = !DILocation(line: 31, column: 18, scope: !99)
>> !102 = !DILocation(line: 32, column: 13, scope: !99)
>> !103 = !DILocation(line: 32, column: 15, scope: !99)
>> !104 = !DILocation(line: 32, column: 21, scope: !99)
>> !105 = !DILocation(line: 22, column: 20, scope: !106)
>> !106 = distinct !DILexicalBlock(scope: !91, file: !17, line: 21,
column:
>> 25)
>> !107 = !DILocation(line: 22, column: 13, scope: !106)
>> !108 = !DILocation(line: 21, column: 9, scope: !91)
>> !109 = !DILocation(line: 33, column: 13, scope: !110)
>> !110 = distinct !DILexicalBlock(scope: !99, file: !17, line: 32,
column:
>> 27)
>> !111 = !DILocation(line: 32, column: 9, scope: !99)
>> !112 = !DILocation(line: 24, column: 19, scope: !91)
>> !113 = !DILocation(line: 24, column: 21, scope: !91)
>> !114 = !DILocation(line: 24, column: 18, scope: !91)
>> !115 = !DILocation(line: 25, column: 13, scope: !91)
>> !116 = !DILocation(line: 25, column: 15, scope: !91)
>> !117 = !DILocation(line: 25, column: 21, scope: !91)
>> !118 = !DILocation(line: 19, column: 10, scope: !83)
>> !119 = !DILocation(line: 26, column: 13, scope: !120)
>> !120 = distinct !DILexicalBlock(scope: !91, file: !17, line: 25,
column:
>> 27)
>> !121 = !DILocation(line: 26, column: 18, scope: !120)
>> !122 = !DILocation(line: 26, column: 15, scope: !120)
>> !123 = !DILocation(line: 25, column: 9, scope: !91)
>> !124 = !DILocation(line: 28, column: 9, scope: !91)
>> !125 = !DILocation(line: 28, column: 15, scope: !91)
>> !126 = !DILocation(line: 28, column: 14, scope: !91)
>> !127 = !DILocation(line: 28, column: 11, scope: !91)
>> !128 = !DILocation(line: 29, column: 23, scope: !91)
>> !129 = !DILocation(line: 29, column: 9, scope: !91)
>> !130 = !DILocation(line: 16, column: 5, scope: !65)
>> !131 = distinct !DISubprogram(name: "panic", scope: !17,
file: !17, line:
>> 1, type: !132, isLocal: true, isDefinition: true, scopeLine: 1,
>> isOptimized: true, unit: !1, variables: !140)
>> !132 = !DISubroutineType(types: !133)
>> !133 = !{!30, !134}
>> !134 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&const
[]const
>> u8", baseType: !135, size: 64, align: 64)
>> !135 = !DICompositeType(tag: DW_TAG_structure_type, name:
"[]u8", size:
>> 128, align: 128, elements: !136)
>> !136 = !{!137, !139}
>> !137 = !DIDerivedType(tag: DW_TAG_member, name: "ptr", scope:
!135,
>> baseType: !138, size: 64, align: 64)
>> !138 = !DIDerivedType(tag: DW_TAG_pointer_type, name:
"&u8", baseType:
>> !6, size: 64, align: 64)
>> !139 = !DIDerivedType(tag: DW_TAG_member, name: "len", scope:
!135,
>> baseType: !32, size: 64, align: 64, offset: 64)
>> !140 = !{!141}
>> !141 = !DILocalVariable(name: "msg", arg: 1, scope: !131,
file: !17,
>> line: 1, type: !135)
>> !142 = !DILocation(line: 1, column: 14, scope: !131)
>> !143 = !DILocation(line: 1, column: 45, scope: !144)
>> !144 = distinct !DILexicalBlock(scope: !145, file: !17, line: 1,
column:
>> 43)
>> !145 = distinct !DILexicalBlock(scope: !131, file: !17, line: 1,
column:
>> 14)
>> !146 = !DILocation(line: 1, column: 60, scope: !144)
>> !147 = distinct !DISubprogram(name: "forceEval", scope: !17,
file: !17,
>> line: 39, type: !148, isLocal: true, isDefinition: true, scopeLine: 39,
>> isOptimized: true, unit: !1, variables: !150)
>> !148 = !DISubroutineType(types: !149)
>> !149 = !{!30, !49}
>> !150 = !{!151, !152, !155}
>> !151 = !DILocalVariable(name: "value", arg: 1, scope: !147,
file: !17,
>> line: 39, type: !49)
>> !152 = !DILocalVariable(name: "x", scope: !153, file: !17,
line: 40,
>> type: !49)
>> !153 = distinct !DILexicalBlock(scope: !154, file: !17, line: 39,
column:
>> 30)
>> !154 = distinct !DILexicalBlock(scope: !147, file: !17, line: 39,
column:
>> 18)
>> !155 = !DILocalVariable(name: "p", scope: !156, file: !17,
line: 41,
>> type: !157)
>> !156 = distinct !DILexicalBlock(scope: !153, file: !17, line: 40,
column:
>> 5)
>> !157 = !DIDerivedType(tag: DW_TAG_pointer_type, name:
"&volatile f32",
>> baseType: !49, size: 64, align: 64)
>> !158 = !DILocation(line: 39, column: 18, scope: !147)
>> !159 = !DILocation(line: 40, column: 5, scope: !153)
>> !160 = !DILocation(line: 41, column: 5, scope: !156)
>> !161 = !DILocation(line: 42, column: 5, scope: !162)
>> !162 = distinct !DILexicalBlock(scope: !156, file: !17, line: 41,
column:
>> 5)
>> !163 = !DILocation(line: 42, column: 10, scope: !162)
>> !164 = !DILocation(line: 42, column: 8, scope: !162)
>> !165 = !DILocation(line: 39, column: 30, scope: !154)
>>
>> source:
>> pub fn panic(msg: []const u8) -> noreturn { @breakpoint(); while
(true)
>> {} }
>>
>> pub fn ceil(x: var) -> @typeOf(x) {
>> const T = @typeOf(x);
>> switch (T) {
>> f32 => @inlineCall(ceil32, x),
>> else => @compileError("ceil not implemented for "
++
>> @typeName(T)),
>> }
>> }
>>
>> fn ceil32(x: f32) -> f32 {
>> var u = @bitCast(u32, x);
>> var e = i32((u >> 23) & 0xFF) - 0x7F;
>> var m: u32 = undefined;
>>
>> if (e >= 23) {
>> return x;
>> }
>> else if (e >= 0) {
>> m = 0x007FFFFF >> u32(e);
>> if (u & m == 0) {
>> return x;
>> }
>> forceEval(x + 0x1.0p120);
>> if (u >> 31 == 0) {
>> u += m;
>> }
>> u &= ~m;
>> @bitCast(f32, u)
>> } else {
>> forceEval(x + 0x1.0p120);
>> if (u >> 31 != 0) {
>> return -0.0;
>> } else {
>> 1.0
>> }
>> }
>> }
>> pub fn forceEval(value: f32) {
>> var x: f32 = undefined;
>> const p = @ptrCast(&volatile f32, &x);
>> *p = x;
>> }
>>
>>
>> export fn do_test() -> bool {
>> return ceil(f32(0.0)) == ceil32(0.0);
>> }
>>
>>
>> -----------------------
>>
>> With no optimizations, the do_test function returns true, which is
>> expected. With -O3, the module gets rewritten to:
>>
>>
>>
>>
>>
>>>
>>> --
>>> Mehdi
>>>
>>>
>>
>
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James Y Knight via llvm-dev
2017-Jun-19 16:47 UTC
[llvm-dev] LLVM behavior different depending on function symbol name
On Mon, Jun 19, 2017 at 12:34 PM, Mehdi AMINI via llvm-dev < llvm-dev at lists.llvm.org> wrote:> using `opt --print-after-all -O3` I see that EarlyCSE is interpreting the > call to `ceil` and constant fold: > > *** IR Dump After Early CSE *** > ; Function Attrs: nobuiltin nounwind > define i1 @do_test() #2 { > Entry: > %0 = call fastcc float @ceil(float 0.000000e+00) #6 > %1 = call fastcc float @ceil32(float 0.000000e+00) #6 > %2 = fcmp fast oeq float 0.000000e+00, %1 > ret i1 %2 > } > > So just running `opt -early-cse -debug` seems enough: > > EarlyCSE Simplify: %0 = call fastcc float @ceil(float 0.000000e+00) #6 > to: float 0.000000e+00 > > I suspect it is not correct from EarlyCSE to do that. > >This was actually _just_ fixed: https://reviews.llvm.org/rL305132 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170619/3fd1c227/attachment.html>
Andrew Kelley via llvm-dev
2017-Jun-19 17:42 UTC
[llvm-dev] LLVM behavior different depending on function symbol name
On Mon, Jun 19, 2017 at 12:47 PM, James Y Knight <jyknight at google.com> wrote:> > > On Mon, Jun 19, 2017 at 12:34 PM, Mehdi AMINI via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> using `opt --print-after-all -O3` I see that EarlyCSE is interpreting the >> call to `ceil` and constant fold: >> >> *** IR Dump After Early CSE *** >> ; Function Attrs: nobuiltin nounwind >> define i1 @do_test() #2 { >> Entry: >> %0 = call fastcc float @ceil(float 0.000000e+00) #6 >> %1 = call fastcc float @ceil32(float 0.000000e+00) #6 >> %2 = fcmp fast oeq float 0.000000e+00, %1 >> ret i1 %2 >> } >> >> So just running `opt -early-cse -debug` seems enough: >> >> EarlyCSE Simplify: %0 = call fastcc float @ceil(float 0.000000e+00) #6 >> to: float 0.000000e+00 >> >> I suspect it is not correct from EarlyCSE to do that. >> >> > This was actually _just_ fixed: > https://reviews.llvm.org/rL305132 >Excellent. Is the fix included in llvm 4.0.1? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170619/64c8a810/attachment.html>