[llvm] eed6476 - Reset PAL metadata when AMDGPU traget stream finishes

[Jakub Kuderski via llvm-commits]

Author: Steven Perron
Date: 2020-08-17T10:56:11-04:00
New Revision: eed6476a8744179efe096c8d1fe6d53bf696962f

URL: https://github.com/llvm/llvm-project/commit/eed6476a8744179efe096c8d1fe6d53bf696962f
DIFF: https://github.com/llvm/llvm-project/commit/eed6476a8744179efe096c8d1fe6d53bf696962f.diff

LOG: Reset PAL metadata when AMDGPU traget stream finishes

If the same stream object is used for multiple compiles, the PAL metadata from eariler compilations will leak into later one.  See https://github.com/GPUOpen-Drivers/llpc/issues/882 for how this is happening in LLPC.

No tests were added because multiple compiles will have to happen using the same pass manager, and I do not see a setup for that on the LLVM side.  Let me know if there is a good way to test this.

Reviewed By: nhaehnle

Differential Revision: https://reviews.llvm.org/D85667

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
    llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.cpp
    llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
index d040efe878be..344f22d412e7 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
@@ -168,10 +168,15 @@ AMDGPUTargetAsmStreamer::AMDGPUTargetAsmStreamer(MCStreamer &S,
 
 // A hook for emitting stuff at the end.
 // We use it for emitting the accumulated PAL metadata as directives.
+// The PAL metadata is reset after it is emitted.
 void AMDGPUTargetAsmStreamer::finish() {
   std::string S;
   getPALMetadata()->toString(S);
   OS << S;
+
+  // Reset the pal metadata so its data will not affect a compilation that
+  // reuses this object.
+  getPALMetadata()->reset();
 }
 
 void AMDGPUTargetAsmStreamer::EmitDirectiveAMDGCNTarget(StringRef Target) {
@@ -423,6 +428,7 @@ MCELFStreamer &AMDGPUTargetELFStreamer::getStreamer() {
 
 // A hook for emitting stuff at the end.
 // We use it for emitting the accumulated PAL metadata as a .note record.
+// The PAL metadata is reset after it is emitted.
 void AMDGPUTargetELFStreamer::finish() {
   std::string Blob;
   const char *Vendor = getPALMetadata()->getVendor();
@@ -432,6 +438,10 @@ void AMDGPUTargetELFStreamer::finish() {
     return;
   EmitNote(Vendor, MCConstantExpr::create(Blob.size(), getContext()), Type,
            [&](MCELFStreamer &OS) { OS.emitBytes(Blob); });
+
+  // Reset the pal metadata so its data will not affect a compilation that
+  // reuses this object.
+  getPALMetadata()->reset();
 }
 
 void AMDGPUTargetELFStreamer::EmitNote(

diff  --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.cpp b/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.cpp
index ef010a7ac157..ad67d49b100b 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.cpp
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.cpp
@@ -773,3 +773,9 @@ void AMDGPUPALMetadata::setLegacy() {
   BlobType = ELF::NT_AMD_AMDGPU_PAL_METADATA;
 }
 
+// Erase all PAL metadata.
+void AMDGPUPALMetadata::reset() {
+  MsgPackDoc.clear();
+  Registers = MsgPackDoc.getEmptyNode();
+  HwStages = MsgPackDoc.getEmptyNode();
+}

diff  --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.h b/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.h
index 544ab669d9ae..b089f295364c 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.h
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUPALMetadata.h
@@ -106,6 +106,9 @@ class AMDGPUPALMetadata {
   // Set legacy PAL metadata format.
   void setLegacy();
 
+  // Erase all PAL metadata.
+  void reset();
+
 private:
   // Return whether the blob type is legacy PAL metadata.
   bool isLegacy() const;