From 0a62474830f50b423329470caeb9a4e4da14a607 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 19 Dec 2010 18:35:09 +0000 Subject: [PATCH] generalize the sadd creation code to not require that the sadd formed is half the size of the original type. We can now compile this into a sadd.i8: unsigned char X(char a, char b) { int res = a+b; if ((unsigned )(res+128) > 255U) abort(); return res; } git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122178 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstCombineCompares.cpp | 55 ++++++------------- test/Transforms/InstCombine/overflow.ll | 31 +++++++++-- 2 files changed, 43 insertions(+), 43 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 11426863f61..9f0fa3e740b 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1635,54 +1635,31 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B, TI->getType()->getPrimitiveSizeInBits() > NewWidth) return 0; } - const IntegerType *WideType = cast(CI1->getType()); - unsigned WideWidth = WideType->getBitWidth(); - unsigned NarrowWidth = WideWidth / 2; - const IntegerType *NarrowType = - IntegerType::get(CI1->getContext(), NarrowWidth); - - // NarrowAllOnes and NarrowSignBit are the magic constants used to - // perform an overflow check in the wider type: 0x00..00FF..FF and - // 0x00..0010..00 respectively, where the highest set bit in each is - // what would be the sign bit in the narrower type. - ConstantInt *NarrowAllOnes = cast(ConstantInt::get(WideType, - APInt::getAllOnesValue(NarrowWidth).zext(WideWidth))); - APInt SignBit(WideWidth, 0); - SignBit.setBit(NarrowWidth-1); - ConstantInt *NarrowSignBit = - cast(ConstantInt::get(WideType, SignBit)); - - if (CI1 != NarrowAllOnes || CI2 != NarrowSignBit) - return 0; - - Module *M = I.getParent()->getParent()->getParent(); - - const Type *IntrinsicType = NarrowType; - Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow, - &IntrinsicType, 1); - - BasicBlock *InitialBlock = Builder->GetInsertBlock(); - BasicBlock::iterator InitialInsert = Builder->GetInsertPoint(); - // If the pattern matches, truncate the inputs to the narrower type and // use the sadd_with_overflow intrinsic to efficiently compute both the // result and the overflow bit. - Builder->SetInsertPoint(OrigAdd->getParent(), - BasicBlock::iterator(OrigAdd)); + Module *M = I.getParent()->getParent()->getParent(); + + const Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth); + Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow, + &NewType, 1); + + // Put the new code above the original add, in case there are any uses of the + // add between the add and the compare. + Builder->SetInsertPoint(OrigAdd->getParent(), BasicBlock::iterator(OrigAdd)); - Value *TruncA = Builder->CreateTrunc(A, NarrowType, A->getName()); - Value *TruncB = Builder->CreateTrunc(B, NarrowType, B->getName()); - CallInst *Call = Builder->CreateCall2(F, TruncA, TruncB); - Value *Add = Builder->CreateExtractValue(Call, 0); - Value *ZExt = Builder->CreateZExt(Add, WideType); + Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc"); + Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc"); + CallInst *Call = Builder->CreateCall2(F, TruncA, TruncB, "sadd"); + Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result"); + Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType()); // The inner add was the result of the narrow add, zero extended to the // wider type. Replace it with the result computed by the intrinsic. OrigAdd->replaceAllUsesWith(ZExt); - Builder->SetInsertPoint(InitialBlock, InitialInsert); - - return ExtractValueInst::Create(Call, 1); + // The original icmp gets replaced with the overflow value. + return ExtractValueInst::Create(Call, 1, "sadd.overflow"); } diff --git a/test/Transforms/InstCombine/overflow.ll b/test/Transforms/InstCombine/overflow.ll index da20e2c983d..6a53d27749a 100644 --- a/test/Transforms/InstCombine/overflow.ll +++ b/test/Transforms/InstCombine/overflow.ll @@ -1,7 +1,7 @@ ; RUN: opt -S -instcombine < %s | FileCheck %s ; -declare i32 @throwAnExceptionOrWhatever(...) +declare void @throwAnExceptionOrWhatever() ; CHECK: @test1 define i32 @test1(i32 %a, i32 %b) nounwind ssp { @@ -16,7 +16,7 @@ entry: br i1 %0, label %if.then, label %if.end if.then: - %call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind + tail call void @throwAnExceptionOrWhatever() nounwind br label %if.end if.end: @@ -44,7 +44,7 @@ entry: br i1 %0, label %if.then, label %if.end if.then: - %call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind + tail call void @throwAnExceptionOrWhatever() nounwind br label %if.end if.end: @@ -54,6 +54,7 @@ if.end: } ; CHECK: test3 +; PR8816 ; This is illegal to transform because the high bits of the original add are ; live out. define i64 @test3(i32 %a, i32 %b) nounwind ssp { @@ -67,10 +68,32 @@ entry: br i1 %0, label %if.then, label %if.end if.then: - %call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind + tail call void @throwAnExceptionOrWhatever() nounwind br label %if.end if.end: ret i64 %add ; CHECK: ret i64 } + +; CHECK: @test4 +; Should be able to form an i8 sadd computed in an i32. +define zeroext i8 @test4(i8 signext %a, i8 signext %b) nounwind ssp { +entry: + %conv = sext i8 %a to i32 + %conv2 = sext i8 %b to i32 + %add = add nsw i32 %conv2, %conv + %add4 = add nsw i32 %add, 128 + %cmp = icmp ugt i32 %add4, 255 + br i1 %cmp, label %if.then, label %if.end +; CHECK: llvm.sadd.with.overflow.i8 +if.then: ; preds = %entry + tail call void @throwAnExceptionOrWhatever() nounwind + unreachable + +if.end: ; preds = %entry + %conv7 = trunc i32 %add to i8 + ret i8 %conv7 +; CHECK: ret i8 +} + -- 2.34.1