[PATCH] D123530: Optimize cross block gc.relocate lowering. NFC.

[Denis Antrushin via Phabricator via llvm-commits]

dantrushin updated this revision to Diff 424530.
dantrushin added a comment.

Update test comment lost during merge


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D123530/new/

https://reviews.llvm.org/D123530

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
  llvm/test/CodeGen/X86/statepoint-vreg-details.ll


Index: llvm/test/CodeGen/X86/statepoint-vreg-details.ll
===================================================================
--- llvm/test/CodeGen/X86/statepoint-vreg-details.ll
+++ llvm/test/CodeGen/X86/statepoint-vreg-details.ll
@@ -342,14 +342,14 @@
   ret i8 addrspace(1)* %res
 }
 
-; Show that ISEL of gc.relocate used in other BB does generate extra COPY instruction.
+; Check that ISEL of gc.relocate used in other BB does not generate extra COPY instruction.
 define i1 @test_cross_bb_reloc(i32 addrspace(1)* %a, i1 %external_cond) gc "statepoint-example" {
 ; CHECK-VREG_LABEL: test_cross_bb_reloc:
 ; CHECK-VREG:    bb.0.entry:
 ; CHECK-VREG:      [[VREG:%[^ ]+]]:gr64 = STATEPOINT 0, 0, 0, @return_i1, 2, 0, 2, 0, 2, 0, 2, 1, %2(tied-def 0), 2, 0, 2, 1, 0, 0, csr_64, implicit-def $rsp, implicit-def $ssp, implicit-def $al
-; CHECK-VREG:      [[EXTRA:%[^ ]+]]:gr64 = COPY [[VREG]]
+; CHECK-VREG-NOT:  COPY [[VREG]]
 ; CHECK-VREG:    bb.1.left:
-; CHECK-VREG:      $rdi = COPY [[EXTRA]]
+; CHECK-VREG:      $rdi = COPY [[VREG]]
 ; CHECK-VREG:      CALL64pcrel32 @consume, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp
 ; CHECK-VREG:      $al = COPY %1
 ; CHECK-VREG:      RET 0, $al
Index: llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
+++ llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
@@ -1231,6 +1231,8 @@
     SDValue Relocation = RFV.getCopyFromRegs(DAG, FuncInfo, getCurSDLoc(),
                                              Chain, nullptr, nullptr);
     setValue(&Relocate, Relocation);
+    // Reuse corresponding statepoint register.
+    FuncInfo.ValueMap[&Relocate] = InReg;
     return;
   }
 
@@ -1263,22 +1265,22 @@
 
     assert(SpillLoad.getNode());
     setValue(&Relocate, SpillLoad);
-    return;
-  }
+  } else {
 
-  assert(Record.type == RecordType::NoRelocate);
-  SDValue SD = getValue(DerivedPtr);
+    assert(Record.type == RecordType::NoRelocate);
+    SDValue SD = getValue(DerivedPtr);
 
-  if (SD.isUndef() && SD.getValueType().getSizeInBits() <= 64) {
-    // Lowering relocate(undef) as arbitrary constant. Current constant value
-    // is chosen such that it's unlikely to be a valid pointer.
-    setValue(&Relocate, DAG.getTargetConstant(0xFEFEFEFE, SDLoc(SD), MVT::i64));
-    return;
-  }
+    if (SD.isUndef() && SD.getValueType().getSizeInBits() <= 64) {
+      // Lowering relocate(undef) as arbitrary constant. Current constant value
+      // is chosen such that it's unlikely to be a valid pointer.
+      SD = DAG.getTargetConstant(0xFEFEFEFE, SDLoc(SD), MVT::i64);
+    }
 
-  // We didn't need to spill these special cases (constants and allocas).
-  // See the handling in spillIncomingValueForStatepoint for detail.
-  setValue(&Relocate, SD);
+    // We didn't need to spill these special cases (constants and allocas).
+    // See the handling in spillIncomingValueForStatepoint for detail.
+    setValue(&Relocate, SD);
+  }
+  CopyToExportRegsIfNeeded(&Relocate);
 }
 
 void SelectionDAGBuilder::LowerDeoptimizeCall(const CallInst *CI) {
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1124,8 +1124,9 @@
 
   visit(I.getOpcode(), I);
 
-  if (!I.isTerminator() && !HasTailCall &&
-      !isa<GCStatepointInst>(I)) // statepoints handle their exports internally
+  // statepoints and relocates handle their exports internally
+  if (!I.isTerminator() && !HasTailCall && !isa<GCStatepointInst>(I) &&
+      !isa<GCRelocateInst>(I))
     CopyToExportRegsIfNeeded(&I);
 
   CurInst = nullptr;


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