From 685212e39a1fdb37be164fd8b8e7152cc64e6fb8 Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
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<BitCastInst>(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<Value*, 8> 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<GEPOperator>(GEP)->isInBounds()
- ? Builder->CreateInBoundsGEP(OrigBase, NewIndices)
- : Builder->CreateGEP(
- OrigBase->getType()->getPointerElementType(),
- OrigBase, NewIndices);
- NGEP->takeName(GEP);
-
- if (isa<BitCastInst>(CI))
- return new BitCastInst(NGEP, CI.getType());
- assert(isa<PtrToIntInst>(CI));
- return new PtrToIntInst(NGEP, CI.getType());
- }
- }
}
return commonCastTransforms(CI);
--
2.40.0