6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-21 06:30:16 +00:00
Code Issues Projects Releases Wiki Activity

if a 'with overflow' intrinsic just has the normal result used, simplify

Browse Source 
it to a normal binop.  Patch by Alastair Lynn, testcase by me.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86524 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-11-09 07:07:56 +00:00
parent df8ed02473
commit 7e606e2e98
2 changed files with 53 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -12452,6 +12452,47 @@ Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
return ExtractValueInst::Create(IV->getInsertedValueOperand(),
exti, exte);
}
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
// We're extracting from an intrinsic, see if we're the only user, which
// allows us to simplify multiple result intrinsics to simpler things that
// just get one value..
if (II->hasOneUse()) {
// Check if we're grabbing the overflow bit or the result of a 'with
// overflow' intrinsic. If it's the latter we can remove the intrinsic
// and replace it with a traditional binary instruction.
switch (II->getIntrinsicID()) {
case Intrinsic::uadd_with_overflow:
case Intrinsic::sadd_with_overflow:
if (*EV.idx_begin() == 0) { // Normal result.
Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
II->replaceAllUsesWith(UndefValue::get(II->getType()));
EraseInstFromFunction(*II);
return BinaryOperator::CreateAdd(LHS, RHS);
}
break;
case Intrinsic::usub_with_overflow:
case Intrinsic::ssub_with_overflow:
if (*EV.idx_begin() == 0) { // Normal result.
Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
II->replaceAllUsesWith(UndefValue::get(II->getType()));
EraseInstFromFunction(*II);
return BinaryOperator::CreateSub(LHS, RHS);
}
break;
case Intrinsic::umul_with_overflow:
case Intrinsic::smul_with_overflow:
if (*EV.idx_begin() == 0) { // Normal result.
Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
II->replaceAllUsesWith(UndefValue::get(II->getType()));
EraseInstFromFunction(*II);
return BinaryOperator::CreateMul(LHS, RHS);
}
break;
default:
break;
}
}
}
// Can't simplify extracts from other values. Note that nested extracts are
// already simplified implicitely by the above (extract ( extract (insert) )
// will be translated into extract ( insert ( extract ) ) first and then just

12
test/Transforms/InstCombine/intrinsics.ll Normal file
View File

@ -0,0 +1,12 @@
; RUN: opt %s -instcombine -S | FileCheck %s
declare {i8, i1} @llvm.uadd.with.overflow.i8(i8, i8)
define i8 @test1(i8 %A, i8 %B) {
%x = call {i8, i1} @llvm.uadd.with.overflow.i8(i8 %A, i8 %B)
%y = extractvalue {i8, i1} %x, 0
ret i8 %y
; CHECK: @test1
; CHECK-NEXT: %y = add i8 %A, %B
; CHECK-NEXT: ret i8 %y
}