[WinEH] Relax assertion in the presence of stack realignment

The code is correct as is, but we should test it.

llvm-svn: 249715

llvm/lib/Target/X86/X86FrameLowering.cpp

@@ -2178,12 +2178,9 @@ MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers(
   int EHRegOffset = getFrameIndexReference(MF, FI, UsedReg);
   int EndOffset = -EHRegOffset - EHRegSize;
   FuncInfo.EHRegNodeEndOffset = EndOffset;
-  assert(EndOffset >= 0 &&
-         "end of registration object above normal EBP position!");
 
   if (UsedReg == FramePtr) {
     // ADD $offset, %ebp
-    assert(UsedReg == FramePtr);
     unsigned ADDri = getADDriOpcode(false, EndOffset);
     BuildMI(MBB, MBBI, DL, TII.get(ADDri), FramePtr)
         .addReg(FramePtr)
@@ -2191,8 +2188,9 @@ MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers(
         .setMIFlag(MachineInstr::FrameSetup)
         ->getOperand(3)
         .setIsDead();
-  } else {
-    assert(UsedReg == BasePtr);
+    assert(EndOffset >= 0 &&
+           "end of registration object above normal EBP position!");
+  } else if (UsedReg == BasePtr) {
     // LEA offset(%ebp), %esi
     addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA32r), BasePtr),
                  FramePtr, false, EndOffset)
@@ -2205,6 +2203,8 @@ MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers(
     addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32rm), FramePtr),
                  UsedReg, true, Offset)
         .setMIFlag(MachineInstr::FrameSetup);
+  } else {
+    llvm_unreachable("32-bit frames with WinEH must use FramePtr or BasePtr");
   }
   return MBBI;
 }

llvm/test/CodeGen/X86/win32-seh-catchpad-realign.ll

@@ -0,0 +1,80 @@
+; RUN: llc < %s | FileCheck %s
+
+; The aligned alloca means that we have to realign the stack, which forces the
+; use of ESI to address local variables.
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686--windows-msvc"
+
+; Function Attrs: nounwind
+define void @realigned_try() personality i8* bitcast (i32 (...)* @_except_handler3 to i8*) {
+entry:
+  %x = alloca [4 x i32], align 16
+  %arrayidx = getelementptr inbounds [4 x i32], [4 x i32]* %x, i32 0, i32 0
+  invoke void @useit(i32* %arrayidx)
+          to label %__try.cont unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %entry
+  %pad = catchpad [i8* bitcast (i32 ()* @"\01?filt$0@0@realigned_try@@" to i8*)]
+          to label %__except.ret unwind label %catchendblock
+
+__except.ret:                                     ; preds = %catch.dispatch
+  catchret %pad to label %__try.cont
+
+__try.cont:                                       ; preds = %entry, %__except.ret
+  ret void
+
+catchendblock:                                    ; preds = %catch.dispatch
+  catchendpad unwind to caller
+}
+
+; Function Attrs: nounwind argmemonly
+
+; Function Attrs: nounwind
+define internal i32 @"\01?filt$0@0@realigned_try@@"() {
+entry:
+  ret i32 1
+}
+
+declare void @useit(i32*)
+
+declare i32 @_except_handler3(...)
+
+; CHECK-LABEL: _realigned_try:
+; Prologue
+; CHECK: pushl   %ebp
+; CHECK: movl    %esp, %ebp
+; CHECK: pushl   %ebx
+; CHECK: pushl   %edi
+; CHECK: pushl   %esi
+; CHECK: andl    $-16, %esp
+; CHECK: subl    $64, %esp
+; CHECK: movl    %esp, %esi
+; Spill EBP
+; CHECK: movl    %ebp, 12(%esi)
+; Spill ESP
+; CHECK: movl    %esp, 36(%esi)
+; The state is stored at ESI+56, the end of the node is ESI+60.
+; CHECK: movl    $-1, 56(%esi)
+;
+; __try
+; CHECK: calll _useit
+;
+; Epilogue
+; CHECK: LBB0_1:       # %__try.cont
+; CHECK: leal    -12(%ebp), %esp
+; CHECK: popl    %esi
+; CHECK: popl    %edi
+; CHECK: popl    %ebx
+; CHECK: popl    %ebp
+; CHECK: retl
+;
+; CHECK: LBB0_2:                                 # %catch.dispatch
+; Restore ESP
+; CHECK: movl    -24(%ebp), %esp
+; Recompute ESI by subtracting 60 from the end of the registration node.
+; CHECK: leal    -60(%ebp), %esi
+; Restore EBP
+; CHECK: movl    12(%esi), %ebp
+; Rejoin normal control flow
+; CHECK: jmp     LBB0_1