[llvm] 1de4e56 - [AMDGPU] Don't mark the .note section as ALLOC

[Sebastian Neubauer via llvm-commits]

Author: Sebastian Neubauer
Date: 2020-05-05T14:21:45+02:00
New Revision: 1de4e5693317c1e34cae4740d6c9c6733e5ed3fd

URL: https://github.com/llvm/llvm-project/commit/1de4e5693317c1e34cae4740d6c9c6733e5ed3fd
DIFF: https://github.com/llvm/llvm-project/commit/1de4e5693317c1e34cae4740d6c9c6733e5ed3fd.diff

LOG: [AMDGPU] Don't mark the .note section as ALLOC

Marking a section as ALLOC tells the ELF loader to load the section into memory.
As we do not want to load the notes into VRAM, the flag should not be there.

On AMDHSA, .note is still marked as ALLOC, apparently this is currently
needed for OpenCL (see https://reviews.llvm.org/D74995).

Differential Revision: https://reviews.llvm.org/D76278

Added: 
    llvm/test/CodeGen/AMDGPU/amdpal-elf.ll

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
index 362952fe813f..a699cd31e27f 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
@@ -393,9 +393,9 @@ void AMDGPUTargetAsmStreamer::EmitAmdhsaKernelDescriptor(
 // AMDGPUTargetELFStreamer
 //===----------------------------------------------------------------------===//
 
-AMDGPUTargetELFStreamer::AMDGPUTargetELFStreamer(
-    MCStreamer &S, const MCSubtargetInfo &STI)
-    : AMDGPUTargetStreamer(S), Streamer(S) {
+AMDGPUTargetELFStreamer::AMDGPUTargetELFStreamer(MCStreamer &S,
+                                                 const MCSubtargetInfo &STI)
+    : AMDGPUTargetStreamer(S), Streamer(S), Os(STI.getTargetTriple().getOS()) {
   MCAssembler &MCA = getStreamer().getAssembler();
   unsigned EFlags = MCA.getELFHeaderEFlags();
 
@@ -438,9 +438,15 @@ void AMDGPUTargetELFStreamer::EmitNote(
 
   auto NameSZ = Name.size() + 1;
 
+  unsigned NoteFlags = 0;
+  // TODO Apparently, this is currently needed for OpenCL as mentioned in
+  // https://reviews.llvm.org/D74995
+  if (Os == Triple::AMDHSA)
+    NoteFlags = ELF::SHF_ALLOC;
+
   S.PushSection();
-  S.SwitchSection(Context.getELFSection(
-    ElfNote::SectionName, ELF::SHT_NOTE, ELF::SHF_ALLOC));
+  S.SwitchSection(
+      Context.getELFSection(ElfNote::SectionName, ELF::SHT_NOTE, NoteFlags));
   S.emitInt32(NameSZ);                                        // namesz
   S.emitValue(DescSZ, 4);                                     // descz
   S.emitInt32(NoteType);                                      // type

diff  --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
index 683b3e363b9a..5f89da365de0 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
@@ -133,6 +133,7 @@ class AMDGPUTargetAsmStreamer final : public AMDGPUTargetStreamer {
 
 class AMDGPUTargetELFStreamer final : public AMDGPUTargetStreamer {
   MCStreamer &Streamer;
+  Triple::OSType Os;
 
   void EmitNote(StringRef Name, const MCExpr *DescSize, unsigned NoteType,
                 function_ref<void(MCELFStreamer &)> EmitDesc);

diff  --git a/llvm/test/CodeGen/AMDGPU/amdpal-elf.ll b/llvm/test/CodeGen/AMDGPU/amdpal-elf.ll
new file mode 100644
index 000000000000..412815fb9c82
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/amdpal-elf.ll
@@ -0,0 +1,33 @@
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=kaveri -filetype=obj -mattr=-code-object-v3 | llvm-readobj -symbols -s -sd | FileCheck --check-prefix=ELF %s
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=kaveri -mattr=-code-object-v3 | llvm-mc -filetype=obj -triple amdgcn--amdpal -mcpu=kaveri -mattr=-code-object-v3 | llvm-readobj -symbols -s -sd | FileCheck %s --check-prefix=ELF
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=gfx1010 -mattr=+WavefrontSize32,-WavefrontSize64,-code-object-v3 | FileCheck --check-prefix=GFX10-W32 %s
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=gfx1010 -mattr=-WavefrontSize32,+WavefrontSize64,-code-object-v3 | FileCheck --check-prefix=GFX10-W64 %s
+
+; ELF: Section {
+; ELF: Name: .text
+; ELF: Type: SHT_PROGBITS (0x1)
+; ELF: Flags [ (0x6)
+; ELF: SHF_ALLOC (0x2)
+; ELF: SHF_EXECINSTR (0x4)
+; ELF: }
+
+; ELF: SHT_NOTE
+; ELF: Flags [ (0x0)
+; ELF: ]
+
+; ELF: Symbol {
+; ELF: Name: simple
+; ELF: Size: 36
+; ELF: Section: .text (0x2)
+; ELF: }
+
+; GFX10-W32: NumSGPRsForWavesPerEU: 4
+; GFX10-W32: NumVGPRsForWavesPerEU: 3
+; GFX10-W64: NumSGPRsForWavesPerEU: 2
+; GFX10-W64: NumVGPRsForWavesPerEU: 3
+
+define amdgpu_kernel void @simple(i32 addrspace(1)* %out) {
+entry:
+  store i32 0, i32 addrspace(1)* %out
+  ret void
+}