forked from OSchip/llvm-project
teach phi translation of GEPs to simplify geps like 'gep x, 0'.
This allows us to compile the example from PR5313 into: LBB1_2: ## %bb incl %ecx movb %al, (%rsi) movslq %ecx, %rax movb (%rdi,%rax), %al testb %al, %al jne LBB1_2 instead of: LBB1_2: ## %bb movslq %eax, %rcx incl %eax movb (%rdi,%rcx), %cl movb %cl, (%rsi) movslq %eax, %rcx cmpb $0, (%rdi,%rcx) jne LBB1_2 llvm-svn: 89981
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@ -20,6 +20,7 @@
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#include "llvm/IntrinsicInst.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Function.h"
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#include "llvm/Function.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/STLExtras.h"
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@ -716,7 +717,8 @@ static bool isPHITranslatable(Instruction *Inst) {
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/// PHITranslateForPred - Given a computation that satisfied the
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/// PHITranslateForPred - Given a computation that satisfied the
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/// isPHITranslatable predicate, see if we can translate the computation into
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/// isPHITranslatable predicate, see if we can translate the computation into
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/// the specified predecessor block. If so, return that value.
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/// the specified predecessor block. If so, return that value.
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static Value *PHITranslateForPred(Instruction *Inst, BasicBlock *Pred) {
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static Value *PHITranslateForPred(Instruction *Inst, BasicBlock *Pred,
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const TargetData *TD) {
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if (PHINode *PN = dyn_cast<PHINode>(Inst))
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if (PHINode *PN = dyn_cast<PHINode>(Inst))
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return PN->getIncomingValueForBlock(Pred);
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return PN->getIncomingValueForBlock(Pred);
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@ -751,7 +753,9 @@ static Value *PHITranslateForPred(Instruction *Inst, BasicBlock *Pred) {
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GEPOps.back() = APHIOp = PN->getIncomingValueForBlock(Pred);
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GEPOps.back() = APHIOp = PN->getIncomingValueForBlock(Pred);
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}
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}
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// TODO: Simplify the GEP to handle 'gep x, 0' -> x etc.
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// Simplify the GEP to handle 'gep x, 0' -> x etc.
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if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD))
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return V;
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// Scan to see if we have this GEP available.
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// Scan to see if we have this GEP available.
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for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
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for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
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@ -926,7 +930,7 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
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for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
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for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
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BasicBlock *Pred = *PI;
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BasicBlock *Pred = *PI;
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Value *PredPtr = PHITranslateForPred(PtrInst, Pred);
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Value *PredPtr = PHITranslateForPred(PtrInst, Pred, TD);
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// If PHI translation fails, bail out.
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// If PHI translation fails, bail out.
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if (PredPtr == 0)
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if (PredPtr == 0)
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@ -86,3 +86,29 @@ bb2:
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ret i32 %dv
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ret i32 %dv
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}
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}
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; PR5313
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define i32 @test4(i1 %cond, i32* %b, i32* %c) nounwind {
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; CHECK: @test4
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entry:
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br i1 %cond, label %bb, label %bb1
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bb:
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store i32 4, i32* %b
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br label %bb2
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bb1:
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%c1 = getelementptr i32* %c, i32 7
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store i32 82, i32* %c1
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br label %bb2
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bb2:
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%d = phi i32* [ %c, %bb1 ], [ %b, %bb ]
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%i = phi i32 [ 7, %bb1 ], [ 0, %bb ]
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%d1 = getelementptr i32* %d, i32 %i
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%dv = load i32* %d1
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; CHECK: %dv = phi i32 [ 82, %bb1 ], [ 4, %bb ]
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; CHECK-NOT: load
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; CHECK: ret i32 %dv
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ret i32 %dv
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}
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