From 685212e39a1fdb37be164fd8b8e7152cc64e6fb8 Mon Sep 17 00:00:00 2001 From: David Blaikie Date: Fri, 27 Mar 2015 20:13:55 +0000 Subject: [PATCH] Recommit r233116 better: Remove a redundant instcombine involving bitcasts of geps of bitcasts This just didn't need to be here at all, but the assertion I tried to add wasn't appropriate either - the circumstance isn't impossible, it's just not important to deal with it here - the gep-rooted version of this instcombine will handle this case, we don't need to duplicate it for the case where the gep happens to be used in a bitcast. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233404 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstCombineCasts.cpp | 36 ------------------- 1 file changed, 36 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp index fe544c2f065..bd79a2697c1 100644 --- a/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -1450,42 +1450,6 @@ Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) { CI.setOperand(0, GEP->getOperand(0)); return &CI; } - - // If the GEP has a single use, and the base pointer is a bitcast, and the - // GEP computes a constant offset, see if we can convert these three - // instructions into fewer. This typically happens with unions and other - // non-type-safe code. - unsigned AS = GEP->getPointerAddressSpace(); - unsigned OffsetBits = DL.getPointerSizeInBits(AS); - APInt Offset(OffsetBits, 0); - BitCastInst *BCI = dyn_cast(GEP->getOperand(0)); - if (GEP->hasOneUse() && BCI && GEP->accumulateConstantOffset(DL, Offset)) { - // FIXME: This is insufficiently tested - just a no-crash test - // (test/Transforms/InstCombine/2007-05-14-Crash.ll) - // - // Get the base pointer input of the bitcast, and the type it points to. - Value *OrigBase = BCI->getOperand(0); - SmallVector NewIndices; - if (FindElementAtOffset(OrigBase->getType(), Offset.getSExtValue(), - NewIndices)) { - // FIXME: This codepath is completely untested - could be unreachable - // for all I know. - // If we were able to index down into an element, create the GEP - // and bitcast the result. This eliminates one bitcast, potentially - // two. - Value *NGEP = cast(GEP)->isInBounds() - ? Builder->CreateInBoundsGEP(OrigBase, NewIndices) - : Builder->CreateGEP( - OrigBase->getType()->getPointerElementType(), - OrigBase, NewIndices); - NGEP->takeName(GEP); - - if (isa(CI)) - return new BitCastInst(NGEP, CI.getType()); - assert(isa(CI)); - return new PtrToIntInst(NGEP, CI.getType()); - } - } } return commonCastTransforms(CI); -- 2.34.1