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Fix icmp lowering 

Summary:
During icmp lowering it can happen that a constant value can be larger than expected (see the code around the change).
APInt::getMinSignedBits() must be checked again as the shift before can change the constant sign to positive.
I'm not sure it is the best fix possible though.

Test Plan: Regression test included.

Reviewers: resistor, chandlerc, spatel, hfinkel

Reviewed By: hfinkel

Subscribers: hfinkel, llvm-commits

Differential Revision: http://reviews.llvm.org/D9147

llvm-svn: 237812
This commit is contained in:
Pawel Bylica 2015-05-20 17:21:09 +00:00
parent 2f1637ad85
commit 8011da9628
2 changed files with 52 additions and 1 deletions
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3
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
View File

@ -1730,7 +1730,8 @@ TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
ShiftBits = C1.countTrailingZeros();
}
NewC = NewC.lshr(ShiftBits);
if (ShiftBits && isLegalICmpImmediate(NewC.getSExtValue())) {
if (ShiftBits && NewC.getMinSignedBits() <= 64 &&
isLegalICmpImmediate(NewC.getSExtValue())) {
EVT ShiftTy = DCI.isBeforeLegalize() ?
getPointerTy() : getShiftAmountTy(N0.getValueType());
EVT CmpTy = N0.getValueType();

50
llvm/test/CodeGen/Generic/icmp-illegal.ll Normal file
View File

@ -0,0 +1,50 @@
; RUN: llc < %s | FileCheck %s
; CHECK-LABEL: test_ult
define i1 @test_ult(i256 %a) nounwind {
%1 = icmp ult i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_ule
define i1 @test_ule(i256 %a) nounwind {
%1 = icmp ule i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_ugt
define i1 @test_ugt(i256 %a) nounwind {
%1 = icmp ugt i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_uge
define i1 @test_uge(i256 %a) nounwind {
%1 = icmp uge i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_slt
define i1 @test_slt(i256 %a) nounwind {
%1 = icmp slt i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_sle
define i1 @test_sle(i256 %a) nounwind {
%1 = icmp sle i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_sgt
define i1 @test_sgt(i256 %a) nounwind {
%1 = icmp sgt i256 %a, -6432394258550908438
ret i1 %1
}
; CHECK-LABEL: test_sge
define i1 @test_sge(i256 %a) nounwind {
%1 = icmp sge i256 %a, -6432394258550908438
ret i1 %1
}