diff options
author | Chris Lattner <sabre@nondot.org> | 2010-12-22 08:02:57 +0000 |
---|---|---|
committer | Chris Lattner <sabre@nondot.org> | 2010-12-22 08:02:57 +0000 |
commit | cbf68dfbc0b36de8ef20bb42ce0c7d75cb132fc7 (patch) | |
tree | 6eae5a8ce6203fee8812ca0e51d508d1e07a7823 /lib/CodeGen/SelectionDAG/DAGCombiner.cpp | |
parent | 7a2a7faf9cfdbdf5f1de720385dc8a0009cd60a6 (diff) | |
download | external_llvm-cbf68dfbc0b36de8ef20bb42ce0c7d75cb132fc7.zip external_llvm-cbf68dfbc0b36de8ef20bb42ce0c7d75cb132fc7.tar.gz external_llvm-cbf68dfbc0b36de8ef20bb42ce0c7d75cb132fc7.tar.bz2 |
Fix a bug in ReduceLoadWidth that wasn't handling extending
loads properly. We miscompiled the testcase into:
_test: ## @test
movl $128, (%rdi)
movzbl 1(%rdi), %eax
ret
Now we get a proper:
_test: ## @test
movl $128, (%rdi)
movsbl (%rdi), %eax
movzbl %ah, %eax
ret
This fixes PR8757.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122392 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
-rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 2523bb2..e4f3027 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -4241,12 +4241,15 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) { return SDValue(); } + // At this point, we must have a load or else we can't do the transform. + if (!isa<LoadSDNode>(N0)) return SDValue(); + // If the shift amount is larger than the input type then we're not // accessing any of the loaded bytes. If the load was a zextload/extload // then the result of the shift+trunc is zero/undef (handled elsewhere). // If the load was a sextload then the result is a splat of the sign bit // of the extended byte. This is not worth optimizing for. - if (ShAmt >= VT.getSizeInBits()) + if (ShAmt >= cast<LoadSDNode>(N0)->getMemoryVT().getSizeInBits()) return SDValue(); } } |