libclc: remove __attribute__((assume)) for clspv targets

[rjodinchr]

Instead add a proper attribute in clang, and add convert it to function metadata to keep the information in the IR. The goal is to remove the dependency on attribute((assume)) that should have not be there in the first place.

Ref #84934

[llvmbot]

@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-clang

Author: Romaric Jodin (rjodinchr)

Changes

Instead add a proper attribute in clang, and add convert it to function metadata to keep the information in the IR. The goal is to remove the dependency on attribute((assume)) that should have not be there in the first place.

Ref #84934

---

Full diff: https://github.com/llvm/llvm-project/pull/92126.diff

3 Files Affected:

• (modified) clang/include/clang/Basic/Attr.td (+6)
• (modified) clang/lib/CodeGen/CodeGenFunction.cpp (+5)
• (modified) libclc/generic/include/clc/clcfunc.h (+1-1)

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 52552ba488560..0970110ee581d 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -4561,3 +4561,9 @@ def CodeAlign: StmtAttr {
     static constexpr int MaximumAlignment = 4096;
   }];
 }
+
+def ClspvLibclcBuiltin: DeclOrStmtAttr {
+  let Spellings = [Clang<"clspv_libclc_builtin">];
+  let Documentation = [Undocumented];
+  let SimpleHandler = 1;
+}
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 9f16fcb438557..4c4f368ddeba1 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -979,6 +979,11 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
     EmitKernelMetadata(FD, Fn);
   }
 
+  if (FD && FD->hasAttr<ClspvLibclcBuiltinAttr>()) {
+    Fn->setMetadata("clspv_libclc_builtin",
+                    llvm::MDNode::get(getLLVMContext(), {}));
+  }
+
   // If we are checking function types, emit a function type signature as
   // prologue data.
   if (FD && SanOpts.has(SanitizerKind::Function)) {
diff --git a/libclc/generic/include/clc/clcfunc.h b/libclc/generic/include/clc/clcfunc.h
index ad9eb23f29333..59f45c27019d6 100644
--- a/libclc/generic/include/clc/clcfunc.h
+++ b/libclc/generic/include/clc/clcfunc.h
@@ -8,7 +8,7 @@
 #define _CLC_DEF
 #elif defined(CLC_CLSPV) || defined(CLC_CLSPV64)
 #define _CLC_DEF                                                               \
-  __attribute__((noinline)) __attribute__((assume("clspv_libclc_builtin")))
+  __attribute__((noinline)) __attribute__((clspv_libclc_builtin))
 #else
 #define _CLC_DEF __attribute__((always_inline))
 #endif

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[erichkeane]

Also needs:
-a release note
-A test: At least a test against LLVM-IR (CodeGen test).

[rjodinchr]

@erichkeane, I don't know what you expect for the release note, where should I write something?

[erichkeane]

@erichkeane, I don't know what you expect for the release note, where should I write something?

See ReleaseNotes.rst, find a section that makes sense (probably attribute changes), and write a quick blurb about the attribute, likely a very condensed version of the docs.

[Sirraide]

There’s a test that checks all attributes that we support (Misc/pragma-attribute-supported-attributes-list.test) and which is failing at the moment; you’ll have to add this attribute there as well.

[erichkeane]

Still fine once CI approves

[rjodinchr]

Is there something else needed on my side to get that PR merged?

[erichkeane]

Is there something else needed on my side to get that PR merged?

My apologies, I thought you'd been around LLVM enough that you had merge rights. I've done it now.