[llvm] r212081 - Fix .seh_stackalloc 0

[Reid Kleckner]

Author: rnk
Date: Mon Jun 30 19:42:47 2014
New Revision: 212081

URL: http://llvm.org/viewvc/llvm-project?rev=212081&view=rev
Log:
Fix .seh_stackalloc 0

seh_stackalloc 0 is not representable in Win64 SEH info, so emitting it
is a bug.

Reviewers: rnk

Differential Revision: http://reviews.llvm.org/D4334

Patch by Vadim Chugunov!

Added:
    llvm/trunk/test/MC/COFF/seh-stackalloc-zero.s
Modified:
    llvm/trunk/lib/MC/MCStreamer.cpp
    llvm/trunk/lib/Target/X86/X86FrameLowering.cpp

Modified: llvm/trunk/lib/MC/MCStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCStreamer.cpp?rev=212081&r1=212080&r2=212081&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCStreamer.cpp (original)
+++ llvm/trunk/lib/MC/MCStreamer.cpp Mon Jun 30 19:42:47 2014
@@ -515,6 +515,8 @@ void MCStreamer::EmitWinCFISetFrame(unsi
 
 void MCStreamer::EmitWinCFIAllocStack(unsigned Size) {
   EnsureValidW64UnwindInfo();
+  if (Size == 0)
+    report_fatal_error("Allocation size must be non-zero!");
   if (Size & 7)
     report_fatal_error("Misaligned stack allocation!");
   MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;

Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=212081&r1=212080&r2=212081&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Mon Jun 30 19:42:47 2014
@@ -751,10 +751,13 @@ void X86FrameLowering::emitPrologue(Mach
       SEHFrameOffset += SEHFrameOffset % 16; // ensure alignmant
 
       // This only needs to account for XMM spill slots, GPR slots
-      // are covered by .seh_pushreg's emitted above.
-      BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc))
-          .addImm(SEHFrameOffset - X86FI->getCalleeSavedFrameSize())
-          .setMIFlag(MachineInstr::FrameSetup);
+      // are covered by the .seh_pushreg's emitted above.
+      unsigned Size = SEHFrameOffset - X86FI->getCalleeSavedFrameSize();
+      if (Size) {
+        BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc))
+            .addImm(Size)
+            .setMIFlag(MachineInstr::FrameSetup);
+      }
 
       BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SetFrame))
           .addImm(FramePtr)

Added: llvm/trunk/test/MC/COFF/seh-stackalloc-zero.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/COFF/seh-stackalloc-zero.s?rev=212081&view=auto
==============================================================================
--- llvm/trunk/test/MC/COFF/seh-stackalloc-zero.s (added)
+++ llvm/trunk/test/MC/COFF/seh-stackalloc-zero.s Mon Jun 30 19:42:47 2014
@@ -0,0 +1,11 @@
+// RUN: not llvm-mc -triple x86_64-pc-win32 -filetype=obj %s -o %t.o 2>&1 | FileCheck %s
+
+// CHECK: Allocation size must be non-zero!
+
+    .globl smallFunc
+    .def smallFunc; .scl 2; .type 32; .endef
+    .seh_proc smallFunc
+    .seh_stackalloc 0
+smallFunc:
+    ret
+    .seh_endproc