[PATCH] D124644: [DAGCombiner] reassociationCanBreakAddressingModePattern should check uses of the outer add.

[Craig Topper via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG5f057eaa0ddf: [DAGCombiner] reassociationCanBreakAddressingModePattern should check uses of… (authored by craig.topper).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124644/new/

https://reviews.llvm.org/D124644

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/RISCV/split-offsets.ll


Index: llvm/test/CodeGen/RISCV/split-offsets.ll
===================================================================
--- llvm/test/CodeGen/RISCV/split-offsets.ll
+++ llvm/test/CodeGen/RISCV/split-offsets.ll
@@ -118,3 +118,38 @@
   ret void
 }
 
+; GEPs have been manually split so the base GEP does not get used by any memory
+; instructions. Make sure we use a small offset in each of the stores.
+define void @test3([65536 x i32]* %t) {
+; RV32I-LABEL: test3:
+; RV32I:       # %bb.0: # %entry
+; RV32I-NEXT:    lui a1, 20
+; RV32I-NEXT:    addi a1, a1, -1920
+; RV32I-NEXT:    add a0, a0, a1
+; RV32I-NEXT:    li a1, 2
+; RV32I-NEXT:    sw a1, 4(a0)
+; RV32I-NEXT:    li a1, 3
+; RV32I-NEXT:    sw a1, 8(a0)
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: test3:
+; RV64I:       # %bb.0: # %entry
+; RV64I-NEXT:    lui a1, 20
+; RV64I-NEXT:    addiw a1, a1, -1920
+; RV64I-NEXT:    add a0, a0, a1
+; RV64I-NEXT:    li a1, 2
+; RV64I-NEXT:    sw a1, 4(a0)
+; RV64I-NEXT:    li a1, 3
+; RV64I-NEXT:    sw a1, 8(a0)
+; RV64I-NEXT:    ret
+entry:
+  %0 = bitcast [65536 x i32]* %t to i8*
+  %splitgep = getelementptr i8, i8* %0, i64 80000
+  %1 = getelementptr i8, i8* %splitgep, i64 4
+  %2 = bitcast i8* %1 to i32*
+  %3 = getelementptr i8, i8* %splitgep, i64 8
+  %4 = bitcast i8* %3 to i32*
+  store i32 2, i32* %2, align 4
+  store i32 3, i32* %4, align 4
+  ret void
+}
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -519,7 +519,9 @@
 
     SDValue XformToShuffleWithZero(SDNode *N);
     bool reassociationCanBreakAddressingModePattern(unsigned Opc,
-                                                    const SDLoc &DL, SDValue N0,
+                                                    const SDLoc &DL,
+                                                    SDNode *N,
+                                                    SDValue N0,
                                                     SDValue N1);
     SDValue reassociateOpsCommutative(unsigned Opc, const SDLoc &DL, SDValue N0,
                                       SDValue N1);
@@ -996,6 +998,7 @@
 
 bool DAGCombiner::reassociationCanBreakAddressingModePattern(unsigned Opc,
                                                              const SDLoc &DL,
+                                                             SDNode *N,
                                                              SDValue N0,
                                                              SDValue N1) {
   // Currently this only tries to ensure we don't undo the GEP splits done by
@@ -1025,7 +1028,7 @@
     return false;
   const int64_t CombinedValue = CombinedValueIntVal.getSExtValue();
 
-  for (SDNode *Node : N0->uses()) {
+  for (SDNode *Node : N->uses()) {
     auto LoadStore = dyn_cast<MemSDNode>(Node);
     if (LoadStore) {
       // Is x[offset2] already not a legal addressing mode? If so then
@@ -2447,7 +2450,7 @@
     return NewSel;
 
   // reassociate add
-  if (!reassociationCanBreakAddressingModePattern(ISD::ADD, DL, N0, N1)) {
+  if (!reassociationCanBreakAddressingModePattern(ISD::ADD, DL, N, N0, N1)) {
     if (SDValue RADD = reassociateOps(ISD::ADD, DL, N0, N1, N->getFlags()))
       return RADD;
 


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