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Fix mul expansion to check the correct number of bits for 

zero extension when checking if an unsigned multiply is
safe.

llvm-svn: 48171
This commit is contained in:
Dan Gohman 2008-03-10 20:42:19 +00:00
parent b9e4280e94
commit 272e234477
2 changed files with 30 additions and 4 deletions
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7
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
View File

@ -6436,10 +6436,9 @@ void SelectionDAGLegalize::ExpandOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi){
unsigned InnerBitSize = RH.getValueSizeInBits();
unsigned LHSSB = DAG.ComputeNumSignBits(Op.getOperand(0));
unsigned RHSSB = DAG.ComputeNumSignBits(Op.getOperand(1));
if (DAG.MaskedValueIsZero(Op.getOperand(0),
APInt::getHighBitsSet(OuterBitSize, LHSSB)) &&
DAG.MaskedValueIsZero(Op.getOperand(1),
APInt::getHighBitsSet(OuterBitSize, RHSSB))) {
APInt HighMask = APInt::getHighBitsSet(OuterBitSize, InnerBitSize);
if (DAG.MaskedValueIsZero(Node->getOperand(0), HighMask) &&
DAG.MaskedValueIsZero(Node->getOperand(1), HighMask)) {
// The inputs are both zero-extended.
if (HasUMUL_LOHI) {
// We can emit a umul_lohi.

27
llvm/test/CodeGen/X86/mul-legalize.ll Normal file
View File

@ -0,0 +1,27 @@
; RUN: llvm-as < %s | llc -march=x86 | grep cmov | count 1
; PR2135
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
target triple = "i386-pc-linux-gnu"
@.str = constant [13 x i8] c"c45531m.adb\00\00"
define void @main() {
entry:
%tmp1 = call i1 @report__equal( i32 3, i32 3 )
%b.0 = select i1 %tmp1, i64 35184372088832, i64 0
%tmp7 = mul i64 3, %b.0
%tmp32 = icmp eq i64 %tmp7, 105553116266496
br i1 %tmp32, label %return, label %bb35
bb35:
call void @abort( )
unreachable
return:
ret void
}
define i1 @report__equal(i32 %x, i32 %y) {
%tmp = icmp eq i32 %x, %y
ret i1 %tmp
}
declare void @abort()