Fix miscompile of MS inline assembly with stack realignment

For stack frames requiring realignment, three pointers may be needed:
- ebp to address incoming arguments
- esi (could be any callee-saved register) to address locals
- esp to address outgoing arguments

We would use esi unconditionally without verifying that it did not
conflict with inline assembly.

This change doesn't do the verification, it simply emits a fatal error
on functions that use stack realignment, dynamic SP adjustments, and
inline assembly.

Because stack realignment is common on Windows, we also no longer assume
that MS inline assembly clobbers esp.  Instead, we analyze the inline
instructions for implicit definitions and check if esp is there.  If so,
we require the use of a base pointer and consider it in the condition
above.

Mostly fixes PR16830, but we could try harder to find a non-conflicting
base pointer.

Reviewers: sunfish

Differential Revision: http://llvm-reviews.chandlerc.com/D1317

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196876 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 8 deletions

diff --git a/test/CodeGen/X86/ms-inline-asm.ll b/test/CodeGen/X86/ms-inline-asm.ll
index 5e7ba37b39..779abfeeea 100644
--- a/test/CodeGen/X86/ms-inline-asm.ll
+++ b/test/CodeGen/X86/ms-inline-asm.ll
@@ -5,7 +5,6 @@ entry:
   %0 = tail call i32 asm sideeffect inteldialect "mov eax, $1\0A\09mov $0, eax", "=r,r,~{eax},~{dirflag},~{fpsr},~{flags}"(i32 1) nounwind
   ret i32 %0
 ; CHECK: t1
-; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: mov eax, ecx
@@ -19,7 +18,6 @@ entry:
   call void asm sideeffect inteldialect "mov eax, $$1", "~{eax},~{dirflag},~{fpsr},~{flags}"() nounwind
   ret void
 ; CHECK: t2
-; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: mov eax, 1
@@ -34,7 +32,6 @@ entry:
   call void asm sideeffect inteldialect "mov eax, DWORD PTR [$0]", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"(i32* %V.addr) nounwind
   ret void
 ; CHECK: t3
-; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: mov eax, DWORD PTR {{[[esp]}}
@@ -56,7 +53,6 @@ entry:
   %0 = load i32* %b1, align 4
   ret i32 %0
 ; CHECK: t18
-; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: lea ebx, foo
@@ -76,7 +72,6 @@ entry:
   call void asm sideeffect inteldialect "call $0", "r,~{dirflag},~{fpsr},~{flags}"(void ()* @t19_helper) nounwind
   ret void
 ; CHECK-LABEL: t19:
-; CHECK: movl %esp, %ebp
 ; CHECK: movl ${{_?}}t19_helper, %eax
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
@@ -95,7 +90,6 @@ entry:
   %0 = load i32** %res, align 4
   ret i32* %0
 ; CHECK-LABEL: t30:
-; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: lea edi, dword ptr [{{_?}}results]
@@ -103,8 +97,31 @@ entry:
 ; CHECK: {{## InlineAsm End|#NO_APP}}
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
-; CHECK: mov dword ptr [esi], edi
+; CHECK: mov dword ptr [esp], edi
+; CHECK: .att_syntax
+; CHECK: {{## InlineAsm End|#NO_APP}}
+; CHECK: movl (%esp), %eax
+}
+
+; Stack realignment plus MS inline asm that does *not* adjust the stack is no
+; longer an error.
+
+define i32 @t31() {
+entry:
+  %val = alloca i32, align 16
+  store i32 -1, i32* %val, align 16
+  call void asm sideeffect inteldialect "mov dword ptr $0, esp", "=*m,~{dirflag},~{fpsr},~{flags}"(i32* %val) #1
+  %sp = load i32* %val, align 16
+  ret i32 %sp
+; CHECK-LABEL: t31:
+; CHECK: pushl %ebp
+; CHECK: movl %esp, %ebp
+; CHECK: andl $-16, %esp
+; CHECK: {{## InlineAsm Start|#APP}}
+; CHECK: .intel_syntax
+; CHECK: mov dword ptr [esp], esp
 ; CHECK: .att_syntax
 ; CHECK: {{## InlineAsm End|#NO_APP}}
-; CHECK: movl (%esi), %eax
+; CHECK: movl (%esp), %eax
+; CHECK: ret
 }