[llvm] [SPIRV] Allow multiple FuncParamAttr decoration on the same id. (PR #166782)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-spir-v

Author: Marcos Maronas (maarquitos14)

<details>
<summary>Changes</summary>

According to SPIR-V spec:

> It is invalid to decorate any given <id> or structure member more than one time with the same [decoration](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Decoration), unless explicitly allowed below for a specific decoration.

`FuncParamAttr` explicitly allows multiple uses of the decoration on the same <id>, so this patch honors this.

---
Full diff: https://github.com/llvm/llvm-project/pull/166782.diff


2 Files Affected:

- (modified) llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp (+9-8) 
- (modified) llvm/test/CodeGen/SPIRV/spirv_param_decorations_quals.ll (+3-1) 


``````````diff
diff --git a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
index af76016861761..3deabd68a44ed 100644
--- a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
@@ -249,17 +249,18 @@ static InstrSignature instrToSignature(const MachineInstr &MI,
   InstrSignature Signature{MI.getOpcode()};
   for (unsigned i = 0; i < MI.getNumOperands(); ++i) {
     // The only decorations that can be applied more than once to a given <id>
-    // or structure member are UserSemantic(5635), CacheControlLoadINTEL (6442),
-    // and CacheControlStoreINTEL (6443). For all the rest of decorations, we
-    // will only add to the signature the Opcode, the id to which it applies,
-    // and the decoration id, disregarding any decoration flags. This will
-    // ensure that any subsequent decoration with the same id will be deemed as
-    // a duplicate. Then, at the call site, we will be able to handle duplicates
-    // in the best way.
+    // or structure member are FuncParamAttr (38), UserSemantic (5635),
+    // CacheControlLoadINTEL (6442), and CacheControlStoreINTEL (6443). For all
+    // the rest of decorations, we will only add to the signature the Opcode,
+    // the id to which it applies, and the decoration id, disregarding any
+    // decoration flags. This will ensure that any subsequent decoration with
+    // the same id will be deemed as a duplicate. Then, at the call site, we
+    // will be able to handle duplicates in the best way.
     unsigned Opcode = MI.getOpcode();
     if ((Opcode == SPIRV::OpDecorate) && i >= 2) {
       unsigned DecorationID = MI.getOperand(1).getImm();
-      if (DecorationID != SPIRV::Decoration::UserSemantic &&
+      if (DecorationID != SPIRV::Decoration::FuncParamAttr &&
+          DecorationID != SPIRV::Decoration::UserSemantic &&
           DecorationID != SPIRV::Decoration::CacheControlLoadINTEL &&
           DecorationID != SPIRV::Decoration::CacheControlStoreINTEL)
         continue;
diff --git a/llvm/test/CodeGen/SPIRV/spirv_param_decorations_quals.ll b/llvm/test/CodeGen/SPIRV/spirv_param_decorations_quals.ll
index 260394b658348..fb550bb01a3a2 100644
--- a/llvm/test/CodeGen/SPIRV/spirv_param_decorations_quals.ll
+++ b/llvm/test/CodeGen/SPIRV/spirv_param_decorations_quals.ll
@@ -7,9 +7,11 @@ entry:
 
 ; CHECK-SPIRV: OpDecorate %[[#PId:]] Volatile
 ; CHECK-SPIRV: OpDecorate %[[#PId]] FuncParamAttr NoAlias
+; CHECK-SPIRV: OpDecorate %[[#PId]] FuncParamAttr NoWrite
 ; CHECK-SPIRV: %[[#PId]] = OpFunctionParameter %[[#]]
 
 !7 = !{!"volatile"}
 !8 = !{i32 38, i32 4} ; FuncParamAttr NoAlias
-!9 = !{!8}
+!11 = !{i32 38, i32 6} ; FuncParamAttr NoWrite
+!9 = !{!8, !11}
 !10 = !{!9}

``````````

</details>


https://github.com/llvm/llvm-project/pull/166782