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RegionGenerator: Only introduce subregion.ivs for loops fully within a subregion 

IVs of loops for which the loop header is in the subregion, but not the entire
loop may be incremented outside of the subregion and can consequently not be
kept private to the subregion. Instead, they need to and are modeled as virtual
loops in the iteration domains. As this is the case, generating new subregion
induction variables for such loops is not needed and indeed wrong as they would
hide the virtual induction variables modeled in the scop.

This fixes a miscompile in MultiSource/Benchmarks/Ptrdist/bc and
MultiSource/Benchmarks/nbench/. Thanks Michael and Johannes for their
investiagations and helpful observations regarding this bug.

llvm-svn: 252860
This commit is contained in:
Tobias Grosser 2015-11-12 07:34:09 +00:00
parent 6400fc146e
commit bc29e0b27c
3 changed files with 1 additions and 5 deletions
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2
polly/lib/CodeGen/BlockGenerators.cpp
View File

@ -1141,7 +1141,7 @@ void RegionGenerator::copyStmt(ScopStmt &Stmt, LoopToScevMapT &LTS,
// replacement for SCEVs refering to the old loop.
for (BasicBlock *BB : SeenBlocks) {
Loop *L = LI.getLoopFor(BB);
if (L == nullptr || L->getHeader() != BB)
if (L == nullptr || L->getHeader() != BB || !R->contains(L))
continue;
BasicBlock *BBCopy = BlockMap[BB];

2
polly/test/Isl/CodeGen/non-affine-phi-node-expansion-3.ll
View File

@ -13,11 +13,9 @@ loop:
br i1 %cond0, label %branch1, label %backedge
; CHECK-LABEL: polly.stmt.loop:
; CHECK-NEXT: %polly.subregion.iv = phi i32 [ 0, %polly.stmt.loop.entry ]
; CHECK-NEXT: %p_val0 = fadd float 1.000000e+00, 2.000000e+00
; CHECK-NEXT: %p_val1 = fadd float 1.000000e+00, 2.000000e+00
; CHECK-NEXT: %p_val2 = fadd float 1.000000e+00, 2.000000e+00
; CHECK-NEXT: %polly.subregion.iv.inc = add i32 %polly.subregion.iv, 1
; CHECK-NEXT: store float %p_val0, float* %merge.phiops
; CHECK-NEXT: br i1

2
polly/test/Isl/CodeGen/non-affine-phi-node-expansion-4.ll
View File

@ -12,10 +12,8 @@ loop:
br i1 %cond0, label %branch1, label %backedge
; CHECK-LABEL: polly.stmt.loop:
; CHECK-NEXT: %polly.subregion.iv = phi i32 [ 0, %polly.stmt.loop.entry ]
; CHECK-NEXT: %p_val0 = fadd float 1.000000e+00, 2.000000e+00
; CHECK-NEXT: %p_val1 = fadd float 1.000000e+00, 2.000000e+00
; CHECK-NEXT: %polly.subregion.iv.inc = add i32 %polly.subregion.iv, 1
; CHECK-NEXT: store float %p_val0, float* %merge.phiops
; CHECK-NEXT: br i1