[PATCH] D11226: AMDPGU/SI: Negative offsets aren't allowed in MUBUF's vaddr operand

[Tom Stellard]

tstellarAMD created this revision.
tstellarAMD added a reviewer: arsenm.
tstellarAMD added a subscriber: llvm-commits.

http://reviews.llvm.org/D11226

Files:
  lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
  test/CodeGen/AMDGPU/private-memory.ll
  test/CodeGen/AMDGPU/scratch-buffer.ll

Index: test/CodeGen/AMDGPU/scratch-buffer.ll
===================================================================
--- test/CodeGen/AMDGPU/scratch-buffer.ll
+++ test/CodeGen/AMDGPU/scratch-buffer.ll
@@ -85,3 +85,25 @@
   ret void
 }
 
+; CHECK-LABEL: @neg_vaddr_offset
+; Offset stored in vaddr must be postive, so the immediate value cannot be
+; folded into the offset field of the store.  It must be used to compute
+; the value of vaddr.
+; CHECK: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[{{[0-9]+:[0-9]+}}], s{{[0-9]+}} offen{{$}}
+
+define void @neg_vaddr_offset(i32 addrspace(1)* %out, i32 %offset) {
+entry:
+  %array = alloca [8192 x i32]
+  %cmp = icmp slt i32 %offset, 0
+  br i1 %cmp, label %if, label %endif
+
+if:
+  %ptr_offset = add i32 %offset, 4
+  %array_ptr = getelementptr [8192 x i32], [8192 x i32]* %array, i32 0, i32 %ptr_offset
+  store i32 0, i32* %array_ptr
+  br label %endif
+
+endif:
+  ret void
+}
+
Index: test/CodeGen/AMDGPU/private-memory.ll
===================================================================
--- test/CodeGen/AMDGPU/private-memory.ll
+++ test/CodeGen/AMDGPU/private-memory.ll
@@ -298,7 +298,7 @@
 ; FUNC-LABEL: ptrtoint:
 ; SI-NOT: ds_write
 ; SI: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[{{[0-9]+:[0-9]+}}], s{{[0-9]+}} offen
-; SI: buffer_load_dword v{{[0-9]+}}, v{{[0-9]+}}, s[{{[0-9]+:[0-9]+}}], s{{[0-9]+}} offen offset:5
+; SI: buffer_load_dword v{{[0-9]+}}, v{{[0-9]+}}, s[{{[0-9]+:[0-9]+}}], s{{[0-9]+}} offen ;
 define void @ptrtoint(i32 addrspace(1)* %out, i32 %a, i32 %b) {
   %alloca = alloca [16 x i32]
   %tmp0 = getelementptr [16 x i32], [16 x i32]* %alloca, i32 0, i32 %a
Index: lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
===================================================================
--- lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
+++ lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
@@ -1099,13 +1099,16 @@
 
   // (add n0, c1)
   if (CurDAG->isBaseWithConstantOffset(Addr)) {
+    SDValue N0 = Addr.getOperand(0);
     SDValue N1 = Addr.getOperand(1);
-    ConstantSDNode *C1 = cast<ConstantSDNode>(N1);
-
-    if (isLegalMUBUFImmOffset(C1)) {
-      VAddr = Addr.getOperand(0);
-      ImmOffset = CurDAG->getTargetConstant(C1->getZExtValue(), DL, MVT::i16);
-      return true;
+    // Offsets in vaddr must be positive.
+    if (CurDAG->SignBitIsZero(N0)) {
+      ConstantSDNode *C1 = cast<ConstantSDNode>(N1);
+      if (isLegalMUBUFImmOffset(C1)) {
+        VAddr = N0;
+        ImmOffset = CurDAG->getTargetConstant(C1->getZExtValue(), DL, MVT::i16);
+        return true;
+      }
     }
   }
 


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