[clang] [HLSL] Treat `main` as any other function (PR #110546)

[Chris B via cfe-commits]

https://github.com/llvm-beanz created https://github.com/llvm/llvm-project/pull/110546

HLSL doesn't distinguish `main` from any other function. It does treat entry points special, but they're not required to be called `main` so we have a different attribute annotation to mark them.

At the moment this change really just changes the mangling of functions named `main` in the Itanium mangling.

Fixes #110517

>From c966c604e8e40ddae4e738d6048bb7f87cfeeb25 Mon Sep 17 00:00:00 2001
From: Chris Bieneman <chris.bieneman at me.com>
Date: Mon, 30 Sep 2024 13:05:09 -0500
Subject: [PATCH] [HLSL] Treat `main` as any other function

HLSL doesn't distinguish `main` from any other function. It does treat
entry points special, but they're not required to be called `main` so
we have a different attribute annotation to mark them.

At the moment this change really just changes the mangling of functions
named `main` in the Itanium mangling.

Fixes #110517
---
 clang/lib/AST/Decl.cpp                                          | 1 +
 .../test/CodeGenHLSL/builtins/wave_get_lane_index_do_while.hlsl | 2 +-
 clang/test/Options/enable_16bit_types_validation_spirv.hlsl     | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index a14b1b33d35efc..84ef9f74582ef6 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3302,6 +3302,7 @@ bool FunctionDecl::isImmediateFunction() const {
 
 bool FunctionDecl::isMain() const {
   return isNamed(this, "main") && !getLangOpts().Freestanding &&
+         !getLangOpts().HLSL &&
          (getDeclContext()->getRedeclContext()->isTranslationUnit() ||
           isExternC());
 }
diff --git a/clang/test/CodeGenHLSL/builtins/wave_get_lane_index_do_while.hlsl b/clang/test/CodeGenHLSL/builtins/wave_get_lane_index_do_while.hlsl
index 9481b0d60a2723..c223b9117e9277 100644
--- a/clang/test/CodeGenHLSL/builtins/wave_get_lane_index_do_while.hlsl
+++ b/clang/test/CodeGenHLSL/builtins/wave_get_lane_index_do_while.hlsl
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
 // RUN:   spirv-pc-vulkan-library %s -emit-llvm -disable-llvm-passes -o - | FileCheck %s
 
-// CHECK: define spir_func void @main() [[A0:#[0-9]+]] {
+// CHECK: define spir_func void @{{.*}}main{{.*}}() [[A0:#[0-9]+]] {
 void main() {
 // CHECK: entry:
 // CHECK:   %[[CT_ENTRY:[0-9]+]] = call token @llvm.experimental.convergence.entry()
diff --git a/clang/test/Options/enable_16bit_types_validation_spirv.hlsl b/clang/test/Options/enable_16bit_types_validation_spirv.hlsl
index aeb7a8369f4034..3e6734011c39ad 100644
--- a/clang/test/Options/enable_16bit_types_validation_spirv.hlsl
+++ b/clang/test/Options/enable_16bit_types_validation_spirv.hlsl
@@ -4,7 +4,7 @@
 // SPIRV: error: '-fnative-half-type' option requires target HLSL Version >= 2018, but HLSL Version is 'hlsl2016'
 
 // valid: "spirv-unknown-vulkan-library"
-// valid: define spir_func void @main() #0 {
+// valid: define spir_func void @{{.*}}main{{.*}}() #0 {
 
 [numthreads(1,1,1)]
 void main()