[llvm-commits] [llvm] r154322 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/X86/pr12360.ll
Rafael Espindola
rafael.espindola at gmail.com
Mon Apr 9 09:06:03 PDT 2012
Author: rafael
Date: Mon Apr 9 11:06:03 2012
New Revision: 154322
URL: http://llvm.org/viewvc/llvm-project?rev=154322&view=rev
Log:
Pattern match a setcc of boolean value with 0 as a truncate.
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
llvm/trunk/test/CodeGen/X86/pr12360.ll
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=154322&r1=154321&r2=154322&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Apr 9 11:06:03 2012
@@ -4408,6 +4408,44 @@
return SDValue();
}
+// isTruncateOf - If N is a truncate of some other value, return true, record
+// the value being truncated in Op and which of Op's bits are zero in KnownZero.
+// This function computes KnownZero to avoid a duplicated call to
+// ComputeMaskedBits in the caller.
+static bool isTruncateOf(SelectionDAG &DAG, SDValue N, SDValue &Op,
+ APInt &KnownZero) {
+ APInt KnownOne;
+ if (N->getOpcode() == ISD::TRUNCATE) {
+ Op = N->getOperand(0);
+ DAG.ComputeMaskedBits(Op, KnownZero, KnownOne);
+ return true;
+ }
+
+ if (N->getOpcode() != ISD::SETCC || N->getValueType(0) != MVT::i1 ||
+ cast<CondCodeSDNode>(N->getOperand(2))->get() != ISD::SETNE)
+ return false;
+
+ SDValue Op0 = N->getOperand(0);
+ SDValue Op1 = N->getOperand(1);
+ assert(Op0.getValueType() == Op1.getValueType());
+
+ ConstantSDNode *COp0 = dyn_cast<ConstantSDNode>(Op0);
+ ConstantSDNode *COp1 = dyn_cast<ConstantSDNode>(Op1);
+ if (COp0 && COp0->getZExtValue() == 0)
+ Op = Op1;
+ else if (COp1 && COp1->getZExtValue() == 0)
+ Op = Op0;
+ else
+ return false;
+
+ DAG.ComputeMaskedBits(Op, KnownZero, KnownOne);
+
+ if (!(KnownZero | APInt(Op.getValueSizeInBits(), 1)).isAllOnesValue())
+ return false;
+
+ return true;
+}
+
SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
@@ -4425,15 +4463,16 @@
// (zext (truncate x)) -> (truncate x)
// This is valid when the truncated bits of x are already zero.
// FIXME: We should extend this to work for vectors too.
- if (N0.getOpcode() == ISD::TRUNCATE && !VT.isVector()) {
- SDValue Op = N0.getOperand(0);
- APInt TruncatedBits
- = APInt::getBitsSet(Op.getValueSizeInBits(),
- N0.getValueSizeInBits(),
- std::min(Op.getValueSizeInBits(),
- VT.getSizeInBits()));
- APInt KnownZero, KnownOne;
- DAG.ComputeMaskedBits(Op, KnownZero, KnownOne);
+ SDValue Op;
+ APInt KnownZero;
+ if (!VT.isVector() && isTruncateOf(DAG, N0, Op, KnownZero)) {
+ APInt TruncatedBits =
+ (Op.getValueSizeInBits() == N0.getValueSizeInBits()) ?
+ APInt(Op.getValueSizeInBits(), 0) :
+ APInt::getBitsSet(Op.getValueSizeInBits(),
+ N0.getValueSizeInBits(),
+ std::min(Op.getValueSizeInBits(),
+ VT.getSizeInBits()));
if (TruncatedBits == (KnownZero & TruncatedBits)) {
if (VT.bitsGT(Op.getValueType()))
return DAG.getNode(ISD::ZERO_EXTEND, N->getDebugLoc(), VT, Op);
Modified: llvm/trunk/test/CodeGen/X86/pr12360.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr12360.ll?rev=154322&r1=154321&r2=154322&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/pr12360.ll (original)
+++ llvm/trunk/test/CodeGen/X86/pr12360.ll Mon Apr 9 11:06:03 2012
@@ -1,14 +1,46 @@
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
define zeroext i1 @f1(i8* %x) {
+; CHECK: f1:
+; CHECK: movb (%rdi), %al
+; CHECK-NEXT: ret
+
entry:
%0 = load i8* %x, align 1, !range !0
%tobool = trunc i8 %0 to i1
ret i1 %tobool
}
-; CHECK: f1:
+define zeroext i1 @f2(i8* %x) {
+; CHECK: f2:
; CHECK: movb (%rdi), %al
; CHECK-NEXT: ret
+entry:
+ %0 = load i8* %x, align 1, !range !0
+ %tobool = icmp ne i8 %0, 0
+ ret i1 %tobool
+}
+
!0 = metadata !{i8 0, i8 2}
+
+
+; check that we don't build a "trunc" from i1 to i1, which would assert.
+define zeroext i1 @f3(i1 %x) {
+; CHECK: f3:
+
+entry:
+ %tobool = icmp ne i1 %x, 0
+ ret i1 %tobool
+}
+
+; check that we don't build a trunc when other bits are needed
+define zeroext i1 @f4(i32 %x) {
+; CHECK: f4:
+; CHECK: and
+
+entry:
+ %y = and i32 %x, 32768
+ %z = icmp ne i32 %y, 0
+ ret i1 %z
+}
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