[PATCH] D144985: [X86] Make `(shift X (xor/sub N-1, Y))` -> `(shift X, (not Y))` check for one use.

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n updated this revision to Diff 501294.
goldstein.w.n added a comment.

Rebase


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D144985/new/

https://reviews.llvm.org/D144985

Files:
  llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
  llvm/test/CodeGen/X86/pr61038.ll


Index: llvm/test/CodeGen/X86/pr61038.ll
===================================================================
--- llvm/test/CodeGen/X86/pr61038.ll
+++ llvm/test/CodeGen/X86/pr61038.ll
@@ -9,28 +9,24 @@
 ; CHECK-BMI2:       # %bb.0: # %entry
 ; CHECK-BMI2-NEXT:    tzcntl %eax, %eax
 ; CHECK-BMI2-NEXT:    movabsq $8589934591, %rcx # imm = 0x1FFFFFFFF
-; CHECK-BMI2-NEXT:    movq $-1, %rdx
+; CHECK-BMI2-NEXT:    movq %rcx, %rdx
 ; CHECK-BMI2-NEXT:    btcq %rax, %rdx
-; CHECK-BMI2-NEXT:    shrxq %rdx, %rcx, %rdx
-; CHECK-BMI2-NEXT:    btcq %rax, %rcx
 ; CHECK-BMI2-NEXT:    xorl %eax, %eax
-; CHECK-BMI2-NEXT:    cmpq $64, %rcx
-; CHECK-BMI2-NEXT:    cmovael %eax, %edx
-; CHECK-BMI2-NEXT:    movl %edx, (%rdi)
+; CHECK-BMI2-NEXT:    cmpq $64, %rdx
+; CHECK-BMI2-NEXT:    shrxq %rdx, %rcx, %rcx
+; CHECK-BMI2-NEXT:    cmovael %eax, %ecx
+; CHECK-BMI2-NEXT:    movl %ecx, (%rdi)
 ; CHECK-BMI2-NEXT:    retq
 ;
 ; CHECK-BMI-LABEL: test_61038:
 ; CHECK-BMI:       # %bb.0: # %entry
 ; CHECK-BMI-NEXT:    tzcntl %eax, %eax
 ; CHECK-BMI-NEXT:    movabsq $8589934591, %rdx # imm = 0x1FFFFFFFF
-; CHECK-BMI-NEXT:    movq %rdx, %rsi
-; CHECK-BMI-NEXT:    btcq %rax, %rsi
-; CHECK-BMI-NEXT:    movq $-1, %rcx
+; CHECK-BMI-NEXT:    movq %rdx, %rcx
 ; CHECK-BMI-NEXT:    btcq %rax, %rcx
-; CHECK-BMI-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; CHECK-BMI-NEXT:    shrq %cl, %rdx
 ; CHECK-BMI-NEXT:    xorl %eax, %eax
-; CHECK-BMI-NEXT:    cmpq $64, %rsi
+; CHECK-BMI-NEXT:    cmpq $64, %rcx
 ; CHECK-BMI-NEXT:    cmovael %eax, %edx
 ; CHECK-BMI-NEXT:    movl %edx, (%rdi)
 ; CHECK-BMI-NEXT:    retq
Index: llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -4007,7 +4007,7 @@
     if (Add1C && Add1C->getAPIntValue().urem(Size) == 0) {
       NewShiftAmt = Add0;
 
-    } else if (ShiftAmt->getOpcode() != ISD::ADD &&
+    } else if (ShiftAmt->getOpcode() != ISD::ADD && ShiftAmt.hasOneUse() &&
                ((Add0C && Add0C->getAPIntValue().urem(Size) == Size - 1) ||
                 (Add1C && Add1C->getAPIntValue().urem(Size) == Size - 1))) {
       // If we are doing a NOT on just the lower bits with (Size*N-1) -/^ X


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