similar to: [LLVMdev] Inline asm bug?

Hi, Apologies this is a bit lengthy. TLDR: I'm using Dragonegg + LLVM 3.2 and uClibc, and am finding that using the Fast register allocator (i.e. -optimize-regalloc=0) causes miscompilation of setsockopt calls (5-arg system calls). The problem doesn't happen with the default register allocation path selected. It can be worked around by manually simplifying the system call setup

Hi, Thx for your help... Here is the IR code: ; ModuleID = 'foo_bar.c' target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" @.str = private unnamed_addr constant [6 x i8] c"MAIN\0A\00", align 1 ; Function Attrs: nounwind uwtable define i32 @main(i32 %argc, i8** %argv) #0 { entry: %retval = alloca i32,

> I expected that this optimization would be picked > up in a cse, gvn, machine-cse or even peepholing pass. > > Comments? At the LLVM IR level this is represented as define i64 @caller() #0 { entry: store i64* @val, i64** @p, align 8, !tbaa !0 store i64 12345123400, i64* @val, align 8, !tbaa !3 %call = tail call i64 @xtr(i64 12345123400) #2 ret i64 %call } Which is

On Aug 2, 2013, at 1:37 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote: >> I expected that this optimization would be picked >> up in a cse, gvn, machine-cse or even peepholing pass. >> >> Comments? > > > At the LLVM IR level this is represented as > > define i64 @caller() #0 { > entry: > store i64* @val, i64** @p, align 8, !tbaa

Are you sure that's it? I commented that block out, rebuilt llvm 3.3, and it still duplicates the constant. My concern is that long constant loads increase code size and if they can be avoided by better targeting it would be a win. My project's application of llvm tends to use a lot of long constants so this can be a significant optimization. I'll do some more debugging now that you

Hi Julien, > On Oct 28, 2014, at 2:14 AM, Rinaldini Julien <julien.rinaldini at heig-vd.ch> wrote: > > Hum, in fact, I'm still a bit lost ;) > > It seems to works in -O0, but in -O1, -O2 and -O3, I got this error (+ the dump of the function): > > # Machine code for function foo: Post SSA > Function Live Ins: %RDI in %vreg7 > > BB#0: derived from LLVM BB

Hi, I've been experimenting with writing a backend for LLVM (3.2) (having already written a frontend http://savourysnax.github.com/EDL), everything was going reasonably ok ( calls/returns, epilogue, prologue, etc are all working), up until I tried to place support for conditional branches. Given this simple program : int test(int c,int d) { if (c) { return

Thanks for spelling it out, now I understand. On Jun 5, 2011, at 6:11 AM, Galanov, Sergey wrote: > Well, the point is CMOV_GR* are marked clobbering EFLAGS conservatively just in case they turn out to be lowered into a sequence containing XOR %reg,%reg which indeed clobbers EFLAGS. This means there might not be any instruction which actually uses this EFLAGS value. This actually looks like a

Well, the point is CMOV_GR* are marked clobbering EFLAGS conservatively just in case they turn out to be lowered into a sequence containing XOR %reg,%reg which indeed clobbers EFLAGS. This means there might not be any instruction which actually uses this EFLAGS value. For an example we can look no further than the actual test which has been disabled after the fix

> How would one express such semantics in LLVM IR with this intrinsic? By definition, %data anmd %passthrough are different IR virtual registers and there are no copy instructions in LLVM IR. You never need to express this semantic in LLVM IR, because in SSA form they are always different SSA defs for the result of the operation versus the inputs to the operation. Someplace late in the CG

Hi, below is an output of "llc -march=r600 -mcpu=cayman -print-before-all -debug-only=regalloc file.shader" command from llvm3.2svn. The register coalescing pass crashes when joining vreg12:sel_z with vreg13 registers, because it tries to access the interval liveness of vreg13... which is undefined. I don't know if it's a bug of the pass, or if my backend should do something

Hi, Consider this MI code from the hexagon backend. ------------------------------------------------------------------ 16B %vreg0<def> = COPY %R0<kill>; IntRegs:%vreg0 32B %vreg1<def> = LDriw %vreg0, 0; mem:LD4[%a],IntRegs:%vreg1,%vreg0 48B %vreg2<def> = LDriw_indexed %vreg0<kill>, 4; mem:LD4[%add.ptr] IntRegs:%vreg2,%vreg0 64B

Ok, after a long detour I am back to where I have started. I think there is a problem at dep DAG construction. Let me try to convince you. Here is the C code we are dealing with: push () { struct xx_stack *stack, *top; for (stack = xx_stack; stack; stack = stack->next) top = stack; yy_instr = top->first; } If the loop never iterates, "top" will have

Hi, I'm still having problems implementing my custom inserter in the X86 backend. I found a solution to my last problem (http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-October/078296.html), by using a virtual register. The binary works when it's compiled in -O0, but not in -O1,-O2,... I really can't figure what I'm doing wrong... Any idea? Here is the code of my custom

On May 14, 2012, at 4:09 PM, "Pranav Bhandarkar" <pranavb at codeaurora.org> wrote: > Hi, > > Consider this MI code from the hexagon backend. > ------------------------------------------------------------------ > 16B %vreg0<def> = COPY %R0<kill>; IntRegs:%vreg0 > 32B %vreg1<def> = LDriw %vreg0, 0; mem:LD4[%a] >

Sergei, Absolutely right, the copy/ldriw should not be reordered. I was attempting to explain that I consider it a phi-elimination bug, not a DAG builder bug. Liveness will also have problems with this code in the long run. To avoid confusion, I filed PR13112: Phi elimination generates uninitialized vreg uses, and disabled the SSA check until its fixes in r158461. However, your C code is also

Andy, You are probably right here - look at this - before phi elimination this code looks much more sane: # *** IR Dump After Live Variable Analysis ***: # Machine code for function push: SSA Function Live Outs: %R0 BB#0: derived from LLVM BB %entry %vreg5<def> = IMPLICIT_DEF; IntRegs:%vreg5 %vreg4<def> = TFRI_V4 <ga:@xx_stack>; IntRegs:%vreg4

On Jun 13, 2012, at 1:15 PM, Sergei Larin <slarin at codeaurora.org> wrote: > Andy, > > You are probably right here – look at this – before phi elimination this code looks much more sane: > > # *** IR Dump After Live Variable Analysis ***: > # Machine code for function push: SSA > Function Live Outs: %R0 > > BB#0: derived from LLVM BB %entry >

Hi, We're having an issue with TailDuplication in our out-of-tree target and it's this PHI-node that seems to be the cause of the trouble: %vreg2<def> = PHI %vreg0, <BB#2>, %vreg1, <BB#3>; rN:%vreg2 aNlh_0_7:%vreg0 aNlh_rN:%vreg1 Note that the defined %vreg2 has register class "rN" while the read %vreg0 has register class "aNlh_0_7".

I've inherited some target code, but there is no SELECT lowering in my target. But somewhere/somehow SELECT is being transformed into a predicated move. I've traced SELECT everywhere in Codegen/SelectionDAG. Any ideas on tracking this down to the point in Codegen lowering/dag-conversion to a predicated series? Again, I do not have a lowering rule in my target for SELECT. If I do a IR