[PATCH] D130537: AMDGPU: Take care of "tied" operand when removeOperand

[Changpeng Fang via Phabricator via llvm-commits]

cfang updated this revision to Diff 447762.
cfang marked an inline comment as done.
cfang added a comment.
Herald added a subscriber: arphaman.

Rename the LIT test to frame-index-elimination-tied-operand.ll as suggested.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130537/new/

https://reviews.llvm.org/D130537

Files:
  llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
  llvm/test/CodeGen/AMDGPU/frame-index-elimination-tied-operand.ll


Index: llvm/test/CodeGen/AMDGPU/frame-index-elimination-tied-operand.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/frame-index-elimination-tied-operand.ll
@@ -0,0 +1,18 @@
+; RUN: llc -march=amdgcn -mcpu=gfx1100 < %s | FileCheck --check-prefix=GCN %s
+
+define amdgpu_kernel void @tied_operand_test() local_unnamed_addr {
+; GCN-LABEL: tied_operand_test:
+; GCN:       ; %bb.0: ; %entry
+; GCN-NEXT:    scratch_load_u16 [[LDRESULT:v[0-9]+]], off, off offset:4
+; GCN-NEXT:    s_waitcnt vmcnt(0)
+; GCN-NEXT:    ds_store_b16 v{{[0-9]+}}, [[LDRESULT]]
+; GCN-NEXT:    s_endpgm
+entry:
+  %scratch = alloca i16, align 4, addrspace(5)
+  %cond = select i1 undef, i16 addrspace(5)* %scratch, i16 addrspace(5)* undef
+  %spec.select = select i1 undef, i16 addrspace(5)* %cond, i16 addrspace(5)* %scratch
+  %dead.load = load i16, i16 addrspace(5)* %spec.select, align 2
+  %flat.scratch.load = load i16, i16 addrspace(5)* %scratch, align 4
+  store i16 %flat.scratch.load, i16 addrspace(3)* undef, align 2
+  ret void
+}
Index: llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -2154,8 +2154,27 @@
             }
 
             if (NewOpc != -1) {
+              // removeOperand doesn't fixup tied operand indexes at it goes, so
+              // it asserts. Untie vdst_in for now and retie them afterwards.
+              int VDstIn = AMDGPU::getNamedOperandIdx(Opc,
+                                                     AMDGPU::OpName::vdst_in);
+              bool TiedVDst = VDstIn != -1 &&
+                              MI->getOperand(VDstIn).isReg() &&
+                              MI->getOperand(VDstIn).isTied();
+              if (TiedVDst)
+                MI->untieRegOperand(VDstIn);
+
               MI->removeOperand(
                   AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::saddr));
+
+              if (TiedVDst) {
+                int NewVDst =
+                    AMDGPU::getNamedOperandIdx(NewOpc, AMDGPU::OpName::vdst);
+                int NewVDstIn =
+                    AMDGPU::getNamedOperandIdx(NewOpc, AMDGPU::OpName::vdst_in);
+                assert (NewVDst != -1 && NewVDstIn != -1 && "Must be tied!");
+                MI->tieOperands(NewVDst, NewVDstIn);
+              }
               MI->setDesc(TII->get(NewOpc));
               return;
             }


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