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Extend ConstantFolding to understand signed overflow variants

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83338 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Phoenix 2009-10-05 22:53:52 +00:00
parent 540b05d227
commit 1614e50d9f
2 changed files with 144 additions and 1 deletions
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24
lib/Analysis/ConstantFolding.cpp
View File

@ -678,6 +678,8 @@ llvm::canConstantFoldCallTo(const Function *F) {
case Intrinsic::cttz:
case Intrinsic::uadd_with_overflow:
case Intrinsic::usub_with_overflow:
case Intrinsic::sadd_with_overflow:
case Intrinsic::ssub_with_overflow:
return true;
default:
return false;
@ -902,6 +904,28 @@ llvm::ConstantFoldCall(Function *F,
};
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
case Intrinsic::sadd_with_overflow: {
Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result.
Constant *Overflow = ConstantExpr::getSelect(
ConstantExpr::getICmp(CmpInst::ICMP_SGT,
ConstantInt::get(Op1->getType(), 0), Op1),
ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op2),
ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op2)); // overflow.
Constant *Ops[] = { Res, Overflow };
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
case Intrinsic::ssub_with_overflow: {
Constant *Res = ConstantExpr::getSub(Op1, Op2); // result.
Constant *Overflow = ConstantExpr::getSelect(
ConstantExpr::getICmp(CmpInst::ICMP_SGT,
ConstantInt::get(Op2->getType(), 0), Op2),
ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op1),
ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op1)); // overflow.
Constant *Ops[] = { Res, Overflow };
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
}
}

121
test/Transforms/ConstProp/overflow-ops.ll
View File

@ -24,7 +24,6 @@ entry:
; CHECK: ret %i8i1 { i8 6, i1 true }
}
;;-----------------------------
;; usub
;;-----------------------------
@ -47,7 +46,127 @@ entry:
; CHECK: ret %i8i1 { i8 -2, i1 true }
}
;;-----------------------------
;; sadd
;;-----------------------------
define {i8, i1} @sadd_1() nounwind {
entry:
%t = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 42, i8 2)
ret {i8, i1} %t
; CHECK: @sadd_1
; CHECK: ret %i8i1 { i8 44, i1 false }
}
define {i8, i1} @sadd_2() nounwind {
entry:
%t = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 120, i8 10)
ret {i8, i1} %t
; CHECK: @sadd_2
; CHECK: ret %i8i1 { i8 -126, i1 true }
}
define {i8, i1} @sadd_3() nounwind {
entry:
%t = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 -120, i8 10)
ret {i8, i1} %t
; CHECK: @sadd_3
; CHECK: ret %i8i1 { i8 -110, i1 false }
}
define {i8, i1} @sadd_4() nounwind {
entry:
%t = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 -120, i8 -10)
ret {i8, i1} %t
; CHECK: @sadd_4
; CHECK: ret %i8i1 { i8 126, i1 true }
}
define {i8, i1} @sadd_5() nounwind {
entry:
%t = call {i8, i1} @llvm.sadd.with.overflow.i8(i8 2, i8 -10)
ret {i8, i1} %t
; CHECK: @sadd_5
; CHECK: ret %i8i1 { i8 -8, i1 false }
}
;;-----------------------------
;; ssub
;;-----------------------------
define {i8, i1} @ssub_1() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 4, i8 2)
ret {i8, i1} %t
; CHECK: @ssub_1
; CHECK: ret %i8i1 { i8 2, i1 false }
}
define {i8, i1} @ssub_2() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 4, i8 6)
ret {i8, i1} %t
; CHECK: @ssub_2
; CHECK: ret %i8i1 { i8 -2, i1 false }
}
define {i8, i1} @ssub_3() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 -10, i8 120)
ret {i8, i1} %t
; CHECK: @ssub_3
; CHECK: ret %i8i1 { i8 126, i1 true }
}
define {i8, i1} @ssub_3b() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 -10, i8 10)
ret {i8, i1} %t
; CHECK: @ssub_3b
; CHECK: ret %i8i1 { i8 -20, i1 false }
}
define {i8, i1} @ssub_4() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 120, i8 -10)
ret {i8, i1} %t
; CHECK: @ssub_4
; CHECK: ret %i8i1 { i8 -126, i1 true }
}
define {i8, i1} @ssub_4b() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 20, i8 -10)
ret {i8, i1} %t
; CHECK: @ssub_4b
; CHECK: ret %i8i1 { i8 30, i1 false }
}
define {i8, i1} @ssub_5() nounwind {
entry:
%t = call {i8, i1} @llvm.ssub.with.overflow.i8(i8 -20, i8 -10)
ret {i8, i1} %t
; CHECK: @ssub_5
; CHECK: ret %i8i1 { i8 -10, i1 false }
}
declare {i8, i1} @llvm.uadd.with.overflow.i8(i8, i8)
declare {i8, i1} @llvm.usub.with.overflow.i8(i8, i8)
declare {i8, i1} @llvm.sadd.with.overflow.i8(i8, i8)
declare {i8, i1} @llvm.ssub.with.overflow.i8(i8, i8)