Fix stack layout for frames larger than 2gb (#84114)

For very large stack frames, the offset from the stack pointer to a local can be more than 2^31 which overflows various `int` offsets in the frame lowering code.

This patch updates the frame lowering code to calculate the offsets as 64-bit values and resolves the overflows, resulting in the correct codegen for very large frames.

Fixes #48911

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 2ee0c3e..9b8ec9b 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1298,8 +1298,8 @@ static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
 namespace {
 
 class FrameEmitterImpl {
-  int CFAOffset = 0;
-  int InitialCFAOffset = 0;
+  int64_t CFAOffset = 0;
+  int64_t InitialCFAOffset = 0;
   bool IsEH;
   MCObjectStreamer &Streamer;
 
@@ -1413,7 +1413,7 @@ void FrameEmitterImpl::emitCFIInstruction(const MCCFIInstruction &Instr) {
     if (!IsEH)
       Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
 
-    int Offset = Instr.getOffset();
+    int64_t Offset = Instr.getOffset();
     if (IsRelative)
       Offset -= CFAOffset;
     Offset = Offset / dataAlignmentFactor;