[LLVM] [MC] Update frame layout & CFI generation to handle frames larger than 2gb (#99263)

Rebase of #84114. I've only included the core changes to frame layout
calculation & CFI generation which sidesteps the regressions found after
merging #84114. Since these changes are a necessary precursor to the
overall fix and are themselves slightly beneficial as CFI is now
generated correctly, I think it is reasonable to merge this first step.

---

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 fixes CFI to use the corrected sizes.

After this patch, additional work is needed to fix offset truncations in
each target's codegen.

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index efafd55..1297dc3 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1299,8 +1299,8 @@ 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;
 
@@ -1414,7 +1414,7 @@ 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;