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[FIX] Do not hoist invariant pointers with non-loaded base ptr in SCoP 

If the base pointer of a load is invariant and defined in the SCoP but
  not loaded we cannot hoist the load as we would not hoist the base
  pointer definition.

  This fixes bug 25237.

llvm-svn: 250663
This commit is contained in:
Johannes Doerfert 2015-10-18 19:49:25 +00:00
parent ba507b04e1
commit bc7cff4c18
2 changed files with 70 additions and 0 deletions
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13
polly/lib/Analysis/ScopInfo.cpp
View File

@ -2545,6 +2545,19 @@ void Scop::hoistInvariantLoads() {
if (MA->isImplicit() || MA->isWrite() || !MA->isAffine())
continue;
// Skip accesses that have an invariant base pointer which is defined but
// not loaded inside the SCoP. This can happened e.g., if a readnone call
// returns a pointer that is used as a base address. However, as we want
// to hoist indirect pointers, we allow the base pointer to be defined in
// the region if it is also a memory access. Hence, if the ScopArrayInfo
// object has a base pointer origin we know the base pointer is loaded and
// that it is invariant, thus it will be hoisted too.
const ScopArrayInfo *SAI = MA->getScopArrayInfo();
if (!SAI->getBasePtrOriginSAI())
if (auto *BasePtrInst = dyn_cast<Instruction>(SAI->getBasePtr()))
if (R.contains(BasePtrInst))
continue;
// Skip accesses in non-affine subregions as they might not be executed
// under the same condition as the entry of the non-affine subregion.
if (BB != MA->getAccessInstruction()->getParent())

57
polly/test/Isl/CodeGen/invariant_verify_function_failed.ll Normal file
View File

@ -0,0 +1,57 @@
; RUN: opt %loadPolly -S -polly-codegen %s | FileCheck %s
;
; This crashed at some point as the pointer returned by the call
; to @__errno_location is invariant and defined in the SCoP but not
; loaded. Therefore it is not hoisted and consequently not available
; at the beginning of the SCoP where we would need it if we would try
; to hoist %tmp. We don't try to hoist %tmp anymore but this test still
; checks that this passes to code generation and produces valid code.
;
; CHECK: polly.start
;
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Function Attrs: nounwind uwtable
define void @fileblobSetFilename() #0 {
entry:
br i1 undef, label %if.end, label %cleanup
if.end: ; preds = %entry
br i1 undef, label %land.lhs.true, label %if.end.18
land.lhs.true: ; preds = %if.end
%call9 = tail call i32* @__errno_location() #2
%tmp = load i32, i32* %call9, align 4, !tbaa !1
br i1 false, label %if.then.12, label %if.end.18
if.then.12: ; preds = %land.lhs.true
br label %if.end.18
if.end.18: ; preds = %if.then.12, %land.lhs.true, %if.end
%fd.0 = phi i32 [ undef, %if.then.12 ], [ undef, %land.lhs.true ], [ undef, %if.end ]
br i1 undef, label %if.then.21, label %if.end.27
if.then.21: ; preds = %if.end.18
unreachable
if.end.27: ; preds = %if.end.18
br label %cleanup
cleanup: ; preds = %if.end.27, %entry
ret void
}
; Function Attrs: nounwind readnone
declare i32* @__errno_location() #1
attributes #0 = { nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #2 = { nounwind readnone }
!llvm.ident = !{!0}
!0 = !{!"clang version 3.8.0 (trunk 250010) (llvm/trunk 250018)"}
!1 = !{!2, !2, i64 0}
!2 = !{!"int", !3, i64 0}
!3 = !{!"omnipotent char", !4, i64 0}
!4 = !{!"Simple C/C++ TBAA"}