[ARM] Fix PR35379 - incorrect unwind information when compiling with -Oz
The patch makes the unwind information not mention registers, which were pushed
solely for the purpose of saving stack adjustment instructions.
Differential revision: https://reviews.llvm.org/D41300
Fixes https://bugs.llvm.org/show_bug.cgi?id=35379
llvm-svn: 321996
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index d3d79fe..e50bbc1 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -1086,6 +1086,8 @@
unsigned StartOp = 2 + 2;
// Use all the operands.
unsigned NumOffset = 0;
+ // Amount of SP adjustment folded into a push.
+ unsigned Pad = 0;
switch (Opc) {
default:
@@ -1107,6 +1109,16 @@
// temporary to workaround PR11902.
if (MO.isImplicit())
continue;
+ // Registers, pushed as a part of folding an SP update into the
+ // push instruction are marked as undef and should not be
+ // restored when unwinding, because the function can modify the
+ // corresponding stack slots.
+ if (MO.isUndef()) {
+ assert(RegList.empty() &&
+ "Pad registers must come before restored ones");
+ Pad += 4;
+ continue;
+ }
RegList.push_back(MO.getReg());
}
break;
@@ -1118,8 +1130,12 @@
RegList.push_back(SrcReg);
break;
}
- if (MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
+ if (MAI->getExceptionHandlingType() == ExceptionHandling::ARM) {
ATS.emitRegSave(RegList, Opc == ARM::VSTMDDB_UPD);
+ // Account for the SP adjustment, folded into the push.
+ if (Pad)
+ ATS.emitPad(Pad);
+ }
} else {
// Changes of stack / frame pointer.
if (SrcReg == ARM::SP) {