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-rw-r--r--lib/Transforms/Scalar/InstructionCombining.cpp66
-rw-r--r--test/Transforms/InstCombine/fold-intophi.ll54
2 files changed, 6 insertions, 114 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 1088684..9147a99 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1985,42 +1985,6 @@ static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
return 0;
}
-// Check whether all the operands of the PHI dominate the PHI node,
-// knowing that the PHI's operands either dominate BB, or are defined in the BB.
-static bool checkPHI(PHINode *PN, BasicBlock *BB)
-{
- BasicBlock *phiBB = PN->getParent();
- for (unsigned i=0;i<PN->getNumIncomingValues();i++) {
- Instruction *I = dyn_cast<Instruction>(PN->getIncomingValue(i));
- if (!I)
- continue;
- BasicBlock *pBB = I->getParent();
- if (pBB == BB) {
- // another PHI in same BB is always before PN (PN is last phi).
- if (isa<PHINode>(I))
- continue;
- // An instruction in the same BB, and not a phi, this is after PN.
- return false;
- }
- if (phiBB == BB)
- continue;
- // We don't have dominator info, so just check that the instruction
- // is not defined in on of the BB on the unique path between BB and phiBB.
- // If there is no such unique path, or pBB equals to one of the BBs on that
- // path we know that this operand doesn't dominate the PHI node.
- BasicBlock *B = PN->getIncomingBlock(i);
- while ((B = B->getUniquePredecessor())) {
- if (pBB == B)
- return false;
- if (B == phiBB)
- break;
- }
- // No unique path -> doesn't dominate
- if (!B)
- return false;
- }
- return true;
-}
/// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
/// has a PHI node as operand #0, see if we can fold the instruction into the
@@ -2072,13 +2036,9 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
// Okay, we can do the transformation: create the new PHI node.
PHINode *NewPN = PHINode::Create(I.getType(), "");
NewPN->reserveOperandSpace(PN->getNumOperands()/2);
- // We must the PHI node as the last PHI, because it may use one of the other
- // PHIs.
- BasicBlock::iterator BBIt = PN;
- while (isa<PHINode>(BBIt)) ++BBIt;
- InsertNewInstBefore(NewPN, *BBIt);
+ InsertNewInstBefore(NewPN, *PN);
+ NewPN->takeName(PN);
- SmallVector<Instruction*, 2> tmpWorklist;
// Next, add all of the operands to the PHI.
if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
// We only currently try to fold the condition of a select when it is a phi,
@@ -2098,7 +2058,7 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
FalseVInPred,
"phitmp", NonConstBB->getTerminator());
- tmpWorklist.push_back(cast<Instruction>(InV));
+ Worklist.Add(cast<Instruction>(InV));
}
NewPN->addIncoming(InV, ThisBB);
}
@@ -2124,7 +2084,8 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
NonConstBB->getTerminator());
else
llvm_unreachable("Unknown binop!");
- tmpWorklist.push_back(cast<Instruction>(InV));
+
+ Worklist.Add(cast<Instruction>(InV));
}
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
}
@@ -2140,26 +2101,11 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
I.getType(), "phitmp",
NonConstBB->getTerminator());
- tmpWorklist.push_back(cast<Instruction>(InV));
+ Worklist.Add(cast<Instruction>(InV));
}
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
}
}
- // The PHI's operands must dominate the PHI, if we can't prove that
- // undo this transformation.
- if (!checkPHI(NewPN, I.getParent())) {
- Worklist.Remove(NewPN);
- NewPN->eraseFromParent();
- while (!tmpWorklist.empty()) {
- tmpWorklist.pop_back_val()->eraseFromParent();
- }
- return 0;
- }
- while (!tmpWorklist.empty()) {
- Worklist.Add(tmpWorklist.pop_back_val());
- }
- NewPN->takeName(PN);
- Worklist.Add(PN);
return ReplaceInstUsesWith(I, NewPN);
}
diff --git a/test/Transforms/InstCombine/fold-intophi.ll b/test/Transforms/InstCombine/fold-intophi.ll
deleted file mode 100644
index 23b482d..0000000
--- a/test/Transforms/InstCombine/fold-intophi.ll
+++ /dev/null
@@ -1,54 +0,0 @@
-; RUN: opt -instcombine -S <%s | FileCheck %s
-; PR5262
-; Make sure the PHI node gets put in a place where all of its operands dominate it
-target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
-target triple = "x86_64-unknown-linux-gnu"
-
-@tmp2 = global i64 0 ; <i64*> [#uses=1]
-
-declare void @use(i64) nounwind
-
-define void @foo(i1) nounwind align 2 {
-; <label>:1
- br i1 %0, label %2, label %3
-
-; <label>:2 ; preds = %1
- br label %3
-
-; <label>:3 ; preds = %2, %1
-; CHECK: <label>:3
-; CHECK-NEXT: %v4 = phi i1 [ false, %2 ], [ true, %1 ]
-; CHECK-NEXT: %v4_ = phi i1 [ true, %2 ], [ false, %1 ]
-; CHECK-NEXT: br label %l8
- %v4 = phi i8 [ 1, %2 ], [ 0, %1 ] ; <i8> [#uses=1]
- %v4_ = phi i8 [ 0, %2 ], [ 1, %1 ] ; <i8> [#uses=1]
- %v5 = icmp eq i8 %v4, 0 ; <i1> [#uses=1]
- %v5_ = icmp eq i8 %v4_, 0 ; <i1> [#uses=1]
- %v6 = load i64* @tmp2, align 8 ; <i64> [#uses=1]
- %v7 = select i1 %v5, i64 0, i64 %v6 ; <i64> [#uses=1]
- br label %l8
-
-l8:
- %v9 = load i64* @tmp2, align 8
- call void @use(i64 %v7)
- br label %l10
-l10:
- %v11 = select i1 %v5_, i64 0, i64 %v9 ; <i64> [#uses=1]
- call void @use(i64 %v11)
- br label %l11
-l11:
- %v12 = load i64* @tmp2, align 8
- %v13 = select i1 %v5_, i64 0, i64 %v12 ; <i64> [#uses=1]
- call void @use(i64 %v13)
- br i1 %0, label %l12, label %l13
-l12:
- br label %l13
-l13:
-;CHECK: l13:
-;CHECK-NEXT: %v14 = phi i64 [ %v12, %l12 ], [ 0, %l11 ]
-;CHECK-NEXT: call void @use(i64 %v14)
- %v14 = phi i1 [0, %l12], [1, %l11]
- %v16 = select i1 %v14, i64 0, i64 %v12 ; <i64> [#uses=1]
- call void @use(i64 %v16)
- ret void
-}
generated by cgit v1.1 at 2025-02-02 05:41:05 +0000