[clang] [AMDGPU] Correctly pass the target-id to `ld.lld` (PR #101037)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Joseph Huber (jhuber6)

<details>
<summary>Changes</summary>

Summary:
The `ld.lld` linker handles LTO, but it does not understand the
target-id syntax some AMDGPU targets use. This patch parses the
target-id and passes the processor name in `-mcpu` and features in
`-mattr`.


---
Full diff: https://github.com/llvm/llvm-project/pull/101037.diff


2 Files Affected:

- (modified) clang/lib/Driver/ToolChains/AMDGPU.cpp (+11-1) 
- (modified) clang/test/Driver/amdgpu-toolchain.c (+3-3) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/AMDGPU.cpp b/clang/lib/Driver/ToolChains/AMDGPU.cpp
index f796c31af8f67..92183ae377516 100644
--- a/clang/lib/Driver/ToolChains/AMDGPU.cpp
+++ b/clang/lib/Driver/ToolChains/AMDGPU.cpp
@@ -634,7 +634,17 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                   C.getDriver().getLTOMode() == LTOK_Thin);
   else if (Args.hasArg(options::OPT_mcpu_EQ))
     CmdArgs.push_back(Args.MakeArgString(
-        "-plugin-opt=mcpu=" + Args.getLastArgValue(options::OPT_mcpu_EQ)));
+        "-plugin-opt=mcpu=" +
+        getProcessorFromTargetID(getToolChain().getTriple(),
+                                 Args.getLastArgValue(options::OPT_mcpu_EQ))));
+
+  // Always pass the target-id features to the LTO job.
+  std::vector<StringRef> Features;
+  getAMDGPUTargetFeatures(C.getDriver(), getToolChain().getTriple(), Args,
+                          Features);
+  if (!Features.empty())
+    CmdArgs.push_back(
+        Args.MakeArgString("-plugin-opt=-mattr=" + llvm::join(Features, ",")));
 
   addGPULibraries(getToolChain(), Args, CmdArgs);
 
diff --git a/clang/test/Driver/amdgpu-toolchain.c b/clang/test/Driver/amdgpu-toolchain.c
index ebd1158b63074..b60d31bae6270 100644
--- a/clang/test/Driver/amdgpu-toolchain.c
+++ b/clang/test/Driver/amdgpu-toolchain.c
@@ -18,12 +18,12 @@
 // AS_LINK_UR: "-cc1as"
 // AS_LINK_UR: ld.lld{{.*}} "--no-undefined"{{.*}} "--unresolved-symbols=ignore-all"
 
-// RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx906 -nogpulib \
+// RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx90a:xnack+:sramecc- -nogpulib \
 // RUN:   -L. -flto -fconvergent-functions %s 2>&1 | FileCheck -check-prefixes=LTO,MCPU %s
-// RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx906 -nogpulib \
+// RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx90a:xnack+:sramecc- -nogpulib \
 // RUN:   -L. -fconvergent-functions %s 2>&1 | FileCheck -check-prefix=MCPU %s
 // LTO: clang{{.*}} "-flto=full"{{.*}}"-fconvergent-functions"
-// MCPU: ld.lld{{.*}}"-L."{{.*}}"-plugin-opt=mcpu=gfx906"
+// MCPU: ld.lld{{.*}}"-L."{{.*}}"-plugin-opt=mcpu=gfx90a"{{.*}}"-plugin-opt=-mattr=-sramecc,+xnack"
 
 // RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx906 -nogpulib \
 // RUN:   -fuse-ld=ld %s 2>&1 | FileCheck -check-prefixes=LD %s

``````````

</details>


https://github.com/llvm/llvm-project/pull/101037