[AArch64] Don't rename registers with pseudo defs in Ld/St opt.
If the root def of for renaming is a noop-pseudo instruction like kill,
we would end up without a correct def for the renamed register, causing
miscompiles.
This patch conservatively bails out on any pseudo instruction.
This fixes https://bugs.chromium.org/p/chromium/issues/detail?id=1037912#c70
diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index 3156bb4..bc91d62 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -1325,6 +1325,19 @@
// For defs, check if we can rename the first def of RegToRename.
if (FoundDef) {
+ // For some pseudo instructions, we might not generate code in the end
+ // (e.g. KILL) and we would end up without a correct def for the rename
+ // register.
+ // TODO: This might be overly conservative and we could handle those cases
+ // in multiple ways:
+ // 1. Insert an extra copy, to materialize the def.
+ // 2. Skip pseudo-defs until we find an non-pseudo def.
+ if (MI.isPseudo()) {
+ LLVM_DEBUG(dbgs() << " Cannot rename pseudo instruction " << MI
+ << "\n");
+ return false;
+ }
+
for (auto &MOP : MI.operands()) {
if (!MOP.isReg() || !MOP.isDef() || MOP.isDebug() || !MOP.getReg() ||
!TRI->regsOverlap(MOP.getReg(), RegToRename))