[llvm-commits] [llvm] r93127 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineCasts.cpp test/Transforms/InstCombine/cast.ll
Chris Lattner
sabre at nondot.org
Sun Jan 10 12:25:54 PST 2010
Author: lattner
Date: Sun Jan 10 14:25:54 2010
New Revision: 93127
URL: http://llvm.org/viewvc/llvm-project?rev=93127&view=rev
Log:
teach zext optimization how to deal with truncs that don't come from
the zext dest type. This allows us to handle test52/53 in cast.ll,
and allows llvm-gcc to generate much better code for PR4216 in -m64
mode:
_test_bitfield: ## @test_bitfield
orl $32962, %edi
movl %edi, %eax
andl $-25350, %eax
ret
This also fixes a bug handling vector extends, ensuring that the
mask produced is a vector constant, not an integer constant.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/trunk/test/Transforms/InstCombine/cast.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=93127&r1=93126&r2=93127&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Sun Jan 10 14:25:54 2010
@@ -192,7 +192,9 @@
return I->getOperand(0);
// Otherwise, must be the same type of cast, so just reinsert a new one.
- Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
+ // This also handles the case of zext(trunc(x)) -> zext(x).
+ Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
+ Opc == Instruction::SExt);
break;
case Instruction::Select: {
Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
@@ -597,6 +599,10 @@
unsigned Opc = I->getOpcode();
switch (Opc) {
+ case Instruction::ZExt: // zext(zext(x)) -> zext(x).
+ case Instruction::SExt: // zext(sext(x)) -> sext(x).
+ case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
+ return true;
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
@@ -608,9 +614,6 @@
CanEvaluateZExtd(I->getOperand(1), Ty, TD);
//case Instruction::LShr:
- case Instruction::ZExt: // zext(zext(x)) -> zext(x).
- case Instruction::SExt: // zext(sext(x)) -> sext(x).
- return true;
case Instruction::Select:
return CanEvaluateZExtd(I->getOperand(1), Ty, TD) &&
@@ -671,7 +674,7 @@
return ReplaceInstUsesWith(CI, Res);
// We need to emit an AND to clear the high bits.
- Constant *C = ConstantInt::get(CI.getContext(),
+ Constant *C = ConstantInt::get(Res->getType(),
APInt::getLowBitsSet(DestBitSize, SrcBitSize));
return BinaryOperator::CreateAnd(Res, C);
}
@@ -810,23 +813,20 @@
//case Instruction::LShr: TODO
//case Instruction::Trunc: TODO
- case Instruction::SExt:
- case Instruction::ZExt: {
- // sext(sext(x)) -> sext(x)
- // sext(zext(x)) -> zext(x)
+ case Instruction::SExt: // sext(sext(x)) -> sext(x)
+ case Instruction::ZExt: // sext(zext(x)) -> zext(x)
return true;
- }
case Instruction::Select:
return CanEvaluateSExtd(I->getOperand(1), Ty, TD) &&
CanEvaluateSExtd(I->getOperand(2), Ty, TD);
+
case Instruction::PHI: {
// We can change a phi if we can change all operands. Note that we never
// get into trouble with cyclic PHIs here because we only consider
// instructions with a single use.
PHINode *PN = cast<PHINode>(I);
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (!CanEvaluateSExtd(PN->getIncomingValue(i), Ty, TD)) return false;
- }
return true;
}
default:
Modified: llvm/trunk/test/Transforms/InstCombine/cast.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/cast.ll?rev=93127&r1=93126&r2=93127&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/cast.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/cast.ll Sun Jan 10 14:25:54 2010
@@ -496,6 +496,30 @@
; CHECK-NEXT: %sext = shl i64 %E, 32
; CHECK-NEXT: %F = ashr i64 %sext, 32
; CHECK-NEXT: ret i64 %F
+}
+define i32 @test52(i64 %A) {
+ %B = trunc i64 %A to i16
+ %C = or i16 %B, -32574
+ %D = and i16 %C, -25350
+ %E = zext i16 %D to i32
+ ret i32 %E
+; CHECK: @test52
+; CHECK-NEXT: %B = trunc i64 %A to i32
+; CHECK-NEXT: %C = or i32 %B, 32962
+; CHECK-NEXT: %D = and i32 %C, 40186
+; CHECK-NEXT: ret i32 %D
}
+define i64 @test53(i32 %A) {
+ %B = trunc i32 %A to i16
+ %C = or i16 %B, -32574
+ %D = and i16 %C, -25350
+ %E = zext i16 %D to i64
+ ret i64 %E
+; CHECK: @test53
+; CHECK-NEXT: %B = zext i32 %A to i64
+; CHECK-NEXT: %C = or i64 %B, 32962
+; CHECK-NEXT: %D = and i64 %C, 40186
+; CHECK-NEXT: ret i64 %D
+}
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