Fangqing Du via llvm-dev
2021-Mar-10 03:22 UTC
[llvm-dev] Bug on llvm backend (llc) when the integer type is not power of 2?
Hi all,
When I run cmd '*llc -mtriple=x86_64-linux -filetype=obj tmp.ll -o
tmp.o*'
and '*g++ tmp.o -o exe*' on following llvm-ir, I'll get wrong
output.
Here '%r' and '%zt' should be 0x3FFFD, but output is 0xFFFFFD.
Is this a bug?
If it's a bug, then how can I workaround this? (Any llc option can avoid
this?)
Thanks a lot!
Fangqing
Xilinx Inc.
; ModuleID = 'main7.bc'
source_filename = "main.cpp"
target datalayout
"e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@.str = private unnamed_addr constant [9 x i8] c"adu: %d\0A\00", align
1
; Function Attrs: noinline norecurse optnone uwtable
define i32 @main() #0 {
entry:
%a = alloca i24, align 4
store i24 -3, i24* %a, align 4; 0xFFFFFD
%bc = bitcast i24* %a to i18*
%r = load i18, i18* %bc, align 4
%zt = zext i18 %r to i40; should be 0x3FFFD
;%or = or i40 %zt, 267386880
%call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([9 x i8],
[9 x i8]* @.str, i32 0, i32 0), i18 %r)
%call2 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([9 x i8],
[9 x i8]* @.str, i32 0, i32 0), i40 %zt)
;%call3 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([9 x
i8], [9 x i8]* @.str, i32 0, i32 0), i40 %or)
ret i32 0
}
declare i32 @printf(i8*, ...) #1
attributes #0 = { noinline norecurse optnone uwtable
"correctly-rounded-divide-sqrt-fp-math"="false"
"disable-tail-calls"="false"
"frame-pointer"="all"
"less-precise-fpmad"="false"
"no-infs-fp-math"="false"
"no-jump-tables"="false"
"no-nans-fp-math"="false"
"no-signed-zeros-fp-math"
="false" "no-trapping-math"="false"
"stack-protector-buffer-size"="8"
"target-cpu"="x86-64"
"target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
"unsafe-fp-math"="false"
"use-soft-float"="false" }
attributes #1 = {
"correctly-rounded-divide-sqrt-fp-math"="false"
"disable-tail-calls"="false"
"frame-pointer"="all"
"less-precise-fpmad""false"
"no-infs-fp-math"="false"
"no-nans-fp-math"="false"
"no-signed-zeros-fp-math"="false"
"no-trapping-math"="false"
"stack-protector-buffer-size"="8"
"target-cpu"="x86-64"
"target-features""+fxsr,+mmx,+sse,+sse2,+x87"
"unsafe-fp-math"="false"
"use-soft-float""false" }
!llvm.module.flags = !{!0}
!llvm.ident = !{!1}
!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 7.0.0 "}
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20210309/4e6ba43d/attachment.html>
Craig Topper via llvm-dev
2021-Mar-10 03:28 UTC
[llvm-dev] Bug on llvm backend (llc) when the integer type is not power of 2?
Per the LangRef for load. https://llvm.org/docs/LangRef.html#id208 "When loading a value of a type like i20 with a size that is not an integral number of bytes, the result is undefined if the value was not originally written using a store of the same type." ~Craig On Tue, Mar 9, 2021 at 7:22 PM Fangqing Du via llvm-dev < llvm-dev at lists.llvm.org> wrote:> Hi all, > > When I run cmd '*llc -mtriple=x86_64-linux -filetype=obj tmp.ll -o tmp.o*' > and '*g++ tmp.o -o exe*' on following llvm-ir, I'll get wrong output. > Here '%r' and '%zt' should be 0x3FFFD, but output is 0xFFFFFD. > > Is this a bug? > If it's a bug, then how can I workaround this? (Any llc option can avoid > this?) > > Thanks a lot! > Fangqing > Xilinx Inc. > > ; ModuleID = 'main7.bc' > > source_filename = "main.cpp" > > target datalayout > "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" > > target triple = "x86_64-unknown-linux-gnu" > > > @.str = private unnamed_addr constant [9 x i8] c"adu: %d\0A\00", align 1 > > > ; Function Attrs: noinline norecurse optnone uwtable > > define i32 @main() #0 { > > entry: > > %a = alloca i24, align 4 > > store i24 -3, i24* %a, align 4; 0xFFFFFD > > %bc = bitcast i24* %a to i18* > > %r = load i18, i18* %bc, align 4 > > %zt = zext i18 %r to i40; should be 0x3FFFD > > ;%or = or i40 %zt, 267386880 > > %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([9 x i8], > [9 x i8]* @.str, i32 0, i32 0), i18 %r) > > %call2 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([9 x i8], > [9 x i8]* @.str, i32 0, i32 0), i40 %zt) > > ;%call3 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([9 x > i8], [9 x i8]* @.str, i32 0, i32 0), i40 %or) > > ret i32 0 > > } > > > declare i32 @printf(i8*, ...) #1 > > > attributes #0 = { noinline norecurse optnone uwtable > "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"> "false" "frame-pointer"="all" "less-precise-fpmad"="false" > "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"> "false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" > "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"> "+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"> "false" } > > attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" > "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"> "false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" > "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" > "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"> "+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"> "false" } > > > !llvm.module.flags = !{!0} > > !llvm.ident = !{!1} > > > !0 = !{i32 1, !"wchar_size", i32 4} > > !1 = !{!"clang version 7.0.0 "} > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210309/d9e38bfd/attachment-0001.html>