[AMDGPU] Lower null pointers in static variable initializer

    For amdgcn target Clang generates addrspacecast to represent null pointers in private and local address spaces.

    In LLVM codegen, the static variable initializer is lowered by virtual function AsmPrinter::lowerConstant which is target generic. Since addrspacecast is target specific, AsmPrinter::lowerConst

    This patch overrides AsmPrinter::lowerConstant with AMDGPUAsmPrinter::lowerConstant, which is able to lower the target-specific addrspacecast in the null pointer representation so that -1 is co

    Differential Revision: https://reviews.llvm.org/D29284

llvm-svn: 294265

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.h b/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.h
index e6981943f49..bf0b9543b89 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.h
+++ b/llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.h
@@ -59,6 +59,18 @@ public:
   }
 
   void adjustPassManager(PassManagerBuilder &) override;
+  /// Get the integer value of a null pointer in the given address space.
+  uint64_t getNullPointerValue(unsigned AddrSpace) const {
+    switch(AddrSpace) {
+    case AMDGPUAS::PRIVATE_ADDRESS:
+    case AMDGPUAS::LOCAL_ADDRESS:
+    case AMDGPUAS::REGION_ADDRESS:
+      return -1;
+    default:
+      return 0;
+    }
+  }
+
 };
 
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