[PATCH] D105684: [RegisterCoalescer] Make resolveConflicts aware of earlyclobber

[ShihPo Hung via Phabricator via llvm-commits]

arcbbb updated this revision to Diff 357448.
arcbbb edited the summary of this revision.
arcbbb added a comment.
Herald added subscribers: frasercrmck, luismarques, apazos, sameer.abuasal, s.egerton, Jim, jocewei, PkmX, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, MaskRay, jrtc27, niosHD, sabuasal, simoncook, johnrusso, rbar, asb.

update a test case to show the difference


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105684/new/

https://reviews.llvm.org/D105684

Files:
  llvm/lib/CodeGen/RegisterCoalescer.cpp
  llvm/test/CodeGen/RISCV/rvv/reg-coalescing.mir


Index: llvm/test/CodeGen/RISCV/rvv/reg-coalescing.mir
===================================================================
--- llvm/test/CodeGen/RISCV/rvv/reg-coalescing.mir
+++ llvm/test/CodeGen/RISCV/rvv/reg-coalescing.mir
@@ -9,10 +9,11 @@
     liveins: $x10
     ; CHECK-LABEL: name: test_earlyclobber
     ; CHECK: liveins: $x10
-    ; CHECK: undef %2.sub_vrm2_0:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
-    ; CHECK: %2.sub_vrm2_1:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
+    ; CHECK: undef %0.sub_vrm2_0:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
+    ; CHECK: %0.sub_vrm2_1:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
     ; CHECK: [[PseudoVLE32_V_M2_:%[0-9]+]]:vrm2 = PseudoVLE32_V_M2 $x10, 1, 5
-    ; CHECK: early-clobber %2.sub_vrm2_0:vrn2m2 = PseudoVRGATHER_VI_M2 %2.sub_vrm2_0, 0, 1, 5, implicit $vl, implicit $vtype
+    ; CHECK: undef early-clobber %2.sub_vrm2_0:vrn2m2 = PseudoVRGATHER_VI_M2 %0.sub_vrm2_0, 0, 1, 5, implicit $vl, implicit $vtype
+    ; CHECK: %2.sub_vrm2_1:vrn2m2 = COPY %0.sub_vrm2_1
     ; CHECK: PseudoVSUXSEG2EI32_V_M2_M2 %2, $x10, [[PseudoVLE32_V_M2_]], 1, 5, implicit $vl, implicit $vtype
     undef %0.sub_vrm2_0:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
     %0.sub_vrm2_1:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
Index: llvm/lib/CodeGen/RegisterCoalescer.cpp
===================================================================
--- llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -3025,8 +3025,10 @@
     MachineBasicBlock::iterator MI = MBB->begin();
     if (!VNI->isPHIDef()) {
       MI = Indexes->getInstructionFromIndex(VNI->def);
-      // No need to check the instruction defining VNI for reads.
-      ++MI;
+      if (!VNI->def.isEarlyClobber()) {
+          // No need to check the instruction defining VNI for reads.
+          MI++;
+      }
     }
     assert(!SlotIndex::isSameInstr(VNI->def, TaintExtent.front().first) &&
            "Interference ends on VNI->def. Should have been handled earlier");


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