[llvm] 8a1b5f2 - [llvm-ml] Add support for extern proc

[Alan Zhao via llvm-commits]

Author: Alan Zhao
Date: 2022-05-13T17:20:55-04:00
New Revision: 8a1b5f26808429a157835a8011e6b58fe3361e0f

URL: https://github.com/llvm/llvm-project/commit/8a1b5f26808429a157835a8011e6b58fe3361e0f
DIFF: https://github.com/llvm/llvm-project/commit/8a1b5f26808429a157835a8011e6b58fe3361e0f.diff

LOG: [llvm-ml] Add support for extern proc

EXTERN PROC isn't really well documented in MSVC, so after poking around
it seems as if it's just a regular extern symbol.

Interestingly enough, under MSVC the following is allowed:

extern foo:proc

mov eax, foo

MSVC will output:

mov eax, 0

while llvm-ml will currently output:

mov eax, dword ptr [foo]

(since foo is an extern)

Arguably, llvm-ml's output makes more sense, even though it's
inconsistent with MSVC ml. However, since moving an extern proc symbol
to a register doesn't really make sense in the first place, we'll treat
it as undefined behavior for now.

Reviewed By: epastor

Differential Revision: https://reviews.llvm.org/D125582

Added: 
    

Modified: 
    llvm/lib/MC/MCParser/MasmParser.cpp
    llvm/test/tools/llvm-ml/extern.asm
    llvm/test/tools/llvm-ml/indirect_branch.asm

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/MCParser/MasmParser.cpp b/llvm/lib/MC/MCParser/MasmParser.cpp
index da84a91eddd97..0ba1076f20cf1 100644
--- a/llvm/lib/MC/MCParser/MasmParser.cpp
+++ b/llvm/lib/MC/MCParser/MasmParser.cpp
@@ -6034,10 +6034,12 @@ bool MasmParser::parseDirectiveExtern() {
     SMLoc TypeLoc = getTok().getLoc();
     if (parseIdentifier(TypeName))
       return Error(TypeLoc, "expected type");
-    AsmTypeInfo Type;
-    if (lookUpType(TypeName, Type))
-      return Error(TypeLoc, "unrecognized type");
-    KnownType[Name.lower()] = Type;
+    if (!TypeName.equals_insensitive("proc")) {
+      AsmTypeInfo Type;
+      if (lookUpType(TypeName, Type))
+        return Error(TypeLoc, "unrecognized type");
+      KnownType[Name.lower()] = Type;
+    }
 
     MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
     Sym->setExternal(true);

diff  --git a/llvm/test/tools/llvm-ml/extern.asm b/llvm/test/tools/llvm-ml/extern.asm
index 87cfba48e9488..cec75ad2662ee 100644
--- a/llvm/test/tools/llvm-ml/extern.asm
+++ b/llvm/test/tools/llvm-ml/extern.asm
@@ -1,9 +1,10 @@
 ; RUN: llvm-ml -m32 -filetype=s %s /Fo - | FileCheck %s --check-prefixes=CHECK,CHECK-32
 ; RUN: llvm-ml -m64 -filetype=s %s /Fo - | FileCheck %s --check-prefixes=CHECK,CHECK-64
 
-extern foo : dword, bar : word
+extern foo : dword, bar : word, baz : proc
 ; CHECK: .extern foo
 ; CHECK: .extern bar
+; CHECK: .extern baz
 
 .code
 mov ebx, foo

diff  --git a/llvm/test/tools/llvm-ml/indirect_branch.asm b/llvm/test/tools/llvm-ml/indirect_branch.asm
index 391153b73e993..12c847c47df0e 100644
--- a/llvm/test/tools/llvm-ml/indirect_branch.asm
+++ b/llvm/test/tools/llvm-ml/indirect_branch.asm
@@ -6,6 +6,8 @@ ifdef rax
 else
   extern fn_ref_extern : dword
 endif
+
+extern fn_proc_extern : proc
 extern fn_ref_extern_word : word
 
 .data
@@ -248,3 +250,31 @@ else
   ; CHECK-32: call word ptr [fn_ref_extern_word]
   ; CHECK-32-NEXT: jmp word ptr [fn_ref_extern_word]
 endif
+
+t23:
+call fn_proc_extern
+jmp fn_proc_extern
+; CHECK-LABEL: t23:
+; CHECK: call fn_proc_extern
+
+t24:
+call [fn_proc_extern]
+jmp [fn_proc_extern]
+; CHECK-LABEL: t24:
+; CHECK: call fn_proc_extern
+
+t25:
+; CHECK-LABEL: t25:
+ifdef rax
+  call qword ptr [fn_ref_extern]
+  jmp qword ptr [fn_ref_extern]
+  ; CHECK-64: call qword ptr [rip + fn_ref_extern]
+  ; CHECK-64: jmp qword ptr [rip + fn_ref_extern]
+else
+  call dword ptr [fn_ref_extern]
+  jmp dword ptr [fn_ref_extern]
+  ; CHECK-32: call dword ptr [fn_ref_extern]
+  ; CHECK-32: jmp dword ptr [fn_ref_extern]
+endif
+
+end