[llvm-commits] [llvm] r84754 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/crash.ll test/Transforms/InstCombine/fold-intophi.ll
Torok Edwin
edwintorok at gmail.com
Wed Oct 21 03:49:01 PDT 2009
Author: edwin
Date: Wed Oct 21 05:49:00 2009
New Revision: 84754
URL: http://llvm.org/viewvc/llvm-project?rev=84754&view=rev
Log:
Fix PR5262: when folding select into PHI, make sure all operands are available
in the PHI's Basic Block. This uses a conservative approach, because we don't
have dominator info in instcombine.
Added:
llvm/trunk/test/Transforms/InstCombine/fold-intophi.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/crash.ll
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=84754&r1=84753&r2=84754&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Wed Oct 21 05:49:00 2009
@@ -1985,6 +1985,42 @@
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
@@ -2036,9 +2072,13 @@
// Okay, we can do the transformation: create the new PHI node.
PHINode *NewPN = PHINode::Create(I.getType(), "");
NewPN->reserveOperandSpace(PN->getNumOperands()/2);
- InsertNewInstBefore(NewPN, *PN);
- NewPN->takeName(PN);
+ // 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);
+ 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,
@@ -2058,7 +2098,7 @@
InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
FalseVInPred,
"phitmp", NonConstBB->getTerminator());
- Worklist.Add(cast<Instruction>(InV));
+ tmpWorklist.push_back(cast<Instruction>(InV));
}
NewPN->addIncoming(InV, ThisBB);
}
@@ -2084,8 +2124,7 @@
NonConstBB->getTerminator());
else
llvm_unreachable("Unknown binop!");
-
- Worklist.Add(cast<Instruction>(InV));
+ tmpWorklist.push_back(cast<Instruction>(InV));
}
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
}
@@ -2101,11 +2140,26 @@
InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
I.getType(), "phitmp",
NonConstBB->getTerminator());
- Worklist.Add(cast<Instruction>(InV));
+ tmpWorklist.push_back(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);
}
Modified: llvm/trunk/test/Transforms/InstCombine/crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/crash.ll?rev=84754&r1=84753&r2=84754&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/crash.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/crash.ll Wed Oct 21 05:49:00 2009
@@ -44,3 +44,58 @@
store i32 %ins, i32* %arrayidx20
ret void
}
+
+; PR5262
+ at 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
+ %4 = phi i8 [ 1, %2 ], [ 0, %1 ] ; <i8> [#uses=1]
+ %5 = icmp eq i8 %4, 0 ; <i1> [#uses=1]
+ %6 = load i64* @tmp2, align 8 ; <i64> [#uses=1]
+ %7 = select i1 %5, i64 0, i64 %6 ; <i64> [#uses=1]
+ br label %8
+
+; <label>:8 ; preds = %3
+ call void @use(i64 %7)
+ ret void
+}
+
+%t0 = type { i32, i32 }
+%t1 = type { i32, i32, i32, i32, i32* }
+
+declare %t0* @bar2(i64)
+
+define void @bar3(i1, i1) nounwind align 2 {
+; <label>:2
+ br i1 %1, label %10, label %3
+
+; <label>:3 ; preds = %2
+ %4 = getelementptr inbounds %t0* null, i64 0, i32 1 ; <i32*> [#uses=0]
+ %5 = getelementptr inbounds %t1* null, i64 0, i32 4 ; <i32**> [#uses=1]
+ %6 = load i32** %5, align 8 ; <i32*> [#uses=1]
+ %7 = icmp ne i32* %6, null ; <i1> [#uses=1]
+ %8 = zext i1 %7 to i32 ; <i32> [#uses=1]
+ %9 = add i32 %8, 0 ; <i32> [#uses=1]
+ br label %10
+
+; <label>:10 ; preds = %3, %2
+ %11 = phi i32 [ %9, %3 ], [ 0, %2 ] ; <i32> [#uses=1]
+ br i1 %1, label %12, label %13
+
+; <label>:12 ; preds = %10
+ br label %13
+
+; <label>:13 ; preds = %12, %10
+ %14 = zext i32 %11 to i64 ; <i64> [#uses=1]
+ %15 = tail call %t0* @bar2(i64 %14) nounwind ; <%0*> [#uses=0]
+ ret void
+}
Added: llvm/trunk/test/Transforms/InstCombine/fold-intophi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fold-intophi.ll?rev=84754&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fold-intophi.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/fold-intophi.ll Wed Oct 21 05:49:00 2009
@@ -0,0 +1,54 @@
+; 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"
+
+ at 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
+}
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