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r258690 | jamesm | 2016-01-25 14:49:36 +0000 (Mon, 25 Jan 2016) | 7 lines
[DemandedBits] Fix computation of demanded bits for ICmps
The computation of ICmp demanded bits is independent of the individual operand being evaluated. We simply return a mask consisting of the minimum leading zeroes of both operands.
We were incorrectly passing "I" to ComputeKnownBits - this should be "UserI->getOperand(0)". In cases where we were evaluating the 1th operand, we were taking the minimum leading zeroes of it and itself.
This should fix PR26266.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@258805
91177308-0d34-0410-b5e6-
96231b3b80d8
break;
case Instruction::ICmp:
// Count the number of leading zeroes in each operand.
break;
case Instruction::ICmp:
// Count the number of leading zeroes in each operand.
- ComputeKnownBits(BitWidth, I, UserI->getOperand(1));
+ ComputeKnownBits(BitWidth, UserI->getOperand(0), UserI->getOperand(1));
auto NumLeadingZeroes = std::min(KnownZero.countLeadingOnes(),
KnownZero2.countLeadingOnes());
AB = ~APInt::getHighBitsSet(BitWidth, NumLeadingZeroes);
auto NumLeadingZeroes = std::min(KnownZero.countLeadingOnes(),
KnownZero2.countLeadingOnes());
AB = ~APInt::getHighBitsSet(BitWidth, NumLeadingZeroes);
; CHECK-LABEL: 'test_icmp2'
; CHECK-DAG: DemandedBits: 0x1 for %3 = icmp eq i32 %1, %2
; CHECK-LABEL: 'test_icmp2'
; CHECK-DAG: DemandedBits: 0x1 for %3 = icmp eq i32 %1, %2
-; CHECK-DAG: DemandedBits: 0xFF for %1 = and i32 %a, 255
-; CHECK-DAG: DemandedBits: 0xF for %2 = ashr i32 %1, 4
+; CHECK-DAG: DemandedBits: 0xFFF for %1 = and i32 %a, 255
+; CHECK-DAG: DemandedBits: 0xFF for %2 = ashr i32 %1, 4
define i1 @test_icmp2(i32 %a, i32 %b) {
%1 = and i32 %a, 255
%2 = ashr i32 %1, 4
%3 = icmp eq i32 %1, %2
ret i1 %3
}
define i1 @test_icmp2(i32 %a, i32 %b) {
%1 = and i32 %a, 255
%2 = ashr i32 %1, 4
%3 = icmp eq i32 %1, %2
ret i1 %3
}
+
+; CHECK-LABEL: 'test_icmp3'
+; CHECK-DAG: DemandedBits: 0xFFFFFFFF for %1 = and i32 %a, 255
+; CHECK-DAG: DemandedBits: 0x1 for %2 = icmp eq i32 -1, %1
+define i1 @test_icmp3(i32 %a) {
+ %1 = and i32 %a, 255
+ %2 = icmp eq i32 -1, %1
+ ret i1 %2
+}
fi
svn log -c $rev http://llvm.org/svn/llvm-project/$proj/trunk >> $tempfile 2>&1
fi
svn log -c $rev http://llvm.org/svn/llvm-project/$proj/trunk >> $tempfile 2>&1
echo "# Updating tree"
svn up
echo "# Updating tree"
svn up
svn merge -c -$rev . || exit 1
else
echo "# Merging r$rev into $proj locally"
svn merge -c -$rev . || exit 1
else
echo "# Merging r$rev into $proj locally"
- svn merge -c $rev https://llvm.org/svn/llvm-project/$proj/trunk . || exit 1
+ svn merge -c $rev https://jamesm@llvm.org/svn/llvm-project/$proj/trunk . || exit 1