[clang] 70828d9 - [clang] Alias cc modifier to c (#127719)

[via cfe-commits]

Author: PiJoules
Date: 2025-02-27T11:34:16-08:00
New Revision: 70828d9a919a629f11736139adfcb4ba0198ebe7

URL: https://github.com/llvm/llvm-project/commit/70828d9a919a629f11736139adfcb4ba0198ebe7
DIFF: https://github.com/llvm/llvm-project/commit/70828d9a919a629f11736139adfcb4ba0198ebe7.diff

LOG: [clang] Alias cc modifier to c (#127719)

https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#GenericOperandmodifiers
provides the `c` and `cc` modifiers. GCC 15 introduces the `cc` modifier
which does the same as `c`. This patch lets Clang handle this for
compatibility.

Added: 
    clang/test/AST/cc-modifier.cpp

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/AST/Stmt.cpp
    clang/test/CodeGen/asm.c

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b7225e50d83a3..2b72143482943 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -109,6 +109,8 @@ C23 Feature Support
 Non-comprehensive list of changes in this release
 -------------------------------------------------
 
+- Support parsing the `cc` operand modifier and alias it to the `c` modifier (#GH127719).
+
 New Compiler Flags
 ------------------
 

diff  --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 685c00d0cb44f..c8ff2ecea20cc 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -708,6 +708,13 @@ unsigned GCCAsmStmt::AnalyzeAsmString(SmallVectorImpl<AsmStringPiece>&Pieces,
         DiagOffs = CurPtr-StrStart-1;
         return diag::err_asm_invalid_escape;
       }
+
+      // Specifically handle `cc` which we will alias to `c`.
+      // Note this is the only operand modifier that exists which has two
+      // characters.
+      if (EscapedChar == 'c' && *CurPtr == 'c')
+        CurPtr++;
+
       EscapedChar = *CurPtr++;
     }
 

diff  --git a/clang/test/AST/cc-modifier.cpp b/clang/test/AST/cc-modifier.cpp
new file mode 100644
index 0000000000000..24eb105acd2b7
--- /dev/null
+++ b/clang/test/AST/cc-modifier.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu  %s -verify
+// expected-no-diagnostics
+
+void func();
+void func2();
+
+bool func3() {                                                                                               
+  __asm__("%cc0 = %c1" : : "X"(func), "X"(func2));
+  return func2 == func;
+}                                                                                                                    

diff  --git a/clang/test/CodeGen/asm.c b/clang/test/CodeGen/asm.c
index 10102cc2c4db1..9687c993e6464 100644
--- a/clang/test/CodeGen/asm.c
+++ b/clang/test/CodeGen/asm.c
@@ -284,3 +284,9 @@ void *t33(void *ptr)
   // CHECK: @t33
   // CHECK: %1 = call ptr asm "lea $1, $0", "=r,p,~{dirflag},~{fpsr},~{flags}"(ptr %0)
 }
+
+void t34(void) {
+  __asm__ volatile("T34 CC NAMED MODIFIER: %cc[input]" :: [input] "i" (4));
+  // CHECK: @t34()
+  // CHECK: T34 CC NAMED MODIFIER: ${0:c}
+}