<div dir="ltr">Fires in compiler-rt, according to the bots, so I've reverted in r233121</div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Mar 24, 2015 at 2:31 PM, David Blaikie <span dir="ltr"><<a href="mailto:dblaikie@gmail.com" target="_blank">dblaikie@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: dblaikie<br>
Date: Tue Mar 24 16:31:31 2015<br>
New Revision: 233116<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=233116&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=233116&view=rev</a><br>
Log:<br>
Remove an InstCombine that seems to have become redundant.<br>
<br>
Assert that this doesn't fire - I'll remove all of this later, but just<br>
leaving it in for a while in case this is firing & we just don't have<br>
test coverage.<br>
<br>
Modified:<br>
llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp<br>
llvm/trunk/test/Transforms/InstCombine/2007-05-14-Crash.ll<br>
<br>
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=233116&r1=233115&r2=233116&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=233116&r1=233115&r2=233116&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)<br>
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Tue Mar 24 16:31:31 2015<br>
@@ -1455,35 +1455,20 @@ Instruction *InstCombiner::commonPointer<br>
// GEP computes a constant offset, see if we can convert these three<br>
// instructions into fewer. This typically happens with unions and other<br>
// non-type-safe code.<br>
- unsigned AS = GEP->getPointerAddressSpace();<br>
- unsigned OffsetBits = DL.getPointerSizeInBits(AS);<br>
- APInt Offset(OffsetBits, 0);<br>
+ // Looks like this never actually fires due to bitcast+gep folding happening<br>
+ // in InstCombiner::visitGetElementPtrInst where the bitcast operand to a<br>
+ // gep is folded into the gep if possible, before we consider whether that<br>
+ // gep is used in a bitcast as well.<br>
+ // Let's assert that this wouldn't fire just to be sure.<br>
+#ifndef NDEBUG<br>
+ APInt Offset(DL.getPointerSizeInBits(GEP->getPointerAddressSpace()), 0);<br>
BitCastInst *BCI = dyn_cast<BitCastInst>(GEP->getOperand(0));<br>
- if (GEP->hasOneUse() && BCI && GEP->accumulateConstantOffset(DL, Offset)) {<br>
- // FIXME: This is insufficiently tested - just a no-crash test<br>
- // (test/Transforms/InstCombine/2007-05-14-Crash.ll)<br>
- //<br>
- // Get the base pointer input of the bitcast, and the type it points to.<br>
- Value *OrigBase = BCI->getOperand(0);<br>
- SmallVector<Value*, 8> NewIndices;<br>
- if (FindElementAtOffset(OrigBase->getType(), Offset.getSExtValue(),<br>
- NewIndices)) {<br>
- // FIXME: This codepath is completely untested - could be unreachable<br>
- // for all I know.<br>
- // If we were able to index down into an element, create the GEP<br>
- // and bitcast the result. This eliminates one bitcast, potentially<br>
- // two.<br>
- Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?<br>
- Builder->CreateInBoundsGEP(OrigBase, NewIndices) :<br>
- Builder->CreateGEP(OrigBase, NewIndices);<br>
- NGEP->takeName(GEP);<br>
-<br>
- if (isa<BitCastInst>(CI))<br>
- return new BitCastInst(NGEP, CI.getType());<br>
- assert(isa<PtrToIntInst>(CI));<br>
- return new PtrToIntInst(NGEP, CI.getType());<br>
- }<br>
- }<br>
+ SmallVector<Value *, 8> NewIndices;<br>
+ assert(!BCI || !GEP->hasOneUse() ||<br>
+ !GEP->accumulateConstantOffset(DL, Offset) ||<br>
+ !FindElementAtOffset(BCI->getOperand(0)->getType(),<br>
+ Offset.getSExtValue(), NewIndices));<br>
+#endif<br>
}<br>
<br>
return commonCastTransforms(CI);<br>
<br>
Modified: llvm/trunk/test/Transforms/InstCombine/2007-05-14-Crash.ll<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2007-05-14-Crash.ll?rev=233116&r1=233115&r2=233116&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2007-05-14-Crash.ll?rev=233116&r1=233115&r2=233116&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/test/Transforms/InstCombine/2007-05-14-Crash.ll (original)<br>
+++ llvm/trunk/test/Transforms/InstCombine/2007-05-14-Crash.ll Tue Mar 24 16:31:31 2015<br>
@@ -15,4 +15,10 @@ entry:<br>
ret i8* %tmp35<br>
}<br>
<br>
-<br>
+define i32* @bar(%struct.abc* %abc) {<br>
+entry:<br>
+ %tmp1 = bitcast %struct.abc* %abc to %struct.def*<br>
+ %tmp3 = getelementptr %struct.def, %struct.def* %tmp1, i32 0, i32 1<br>
+ %tmp35 = bitcast %struct.abc* %tmp3 to i32*<br>
+ ret i32* %tmp35<br>
+}<br>
<br>
<br>
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</blockquote></div><br></div>