Stay away from str <undef> in ARMLoadStoreOpt. This pass does not understand
<undef> operands, and can cause scavenger failures when it translates
<kill,undef> to <kill>.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97046 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index 4e2d181..5b4f02d 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -748,11 +748,19 @@
if (MMO->isVolatile())
return false;
- // Unaligned ldr/str is emulated by some kernels, but unaligned ldm/stm is not.
+ // Unaligned ldr/str is emulated by some kernels, but unaligned ldm/stm is
+ // not.
if (MMO->getAlignment() < 4)
return false;
}
+ // str <undef> could probably be eliminated entirely, but for now we just want
+ // to avoid making a mess of it.
+ // FIXME: Use str <undef> as a wildcard to enable better stm folding.
+ if (MI->getNumOperands() > 0 && MI->getOperand(0).isReg() &&
+ MI->getOperand(0).isUndef())
+ return false;
+
int Opcode = MI->getOpcode();
switch (Opcode) {
default: break;