[ValueTracking] Add support for xor/disjoint or in getInvertibleOperands

[goldsteinn]

• [ValueTracking] Add tests for xor/disjoint or in getInvertibleOperands; NFC
• [ValueTracking] Add support for xor/disjoint or in getInvertibleOperands

This strengthens our isKnownNonEqual logic with some fairly
trivial cases.

Proofs: https://alive2.llvm.org/ce/z/4pxRTj

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

@llvm/pr-subscribers-llvm-transforms

Author: None (goldsteinn)

Changes

• [ValueTracking] Add tests for xor/disjoint or in getInvertibleOperands; NFC
• [ValueTracking] Add support for xor/disjoint or in getInvertibleOperands

---

Full diff: https://github.com/llvm/llvm-project/pull/87705.diff

2 Files Affected:

• (modified) llvm/lib/Analysis/ValueTracking.cpp (+14-1)
• (modified) llvm/test/Transforms/InstSimplify/icmp.ll (+79-1)

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 5ad4da43bca7db..885f4b0907ea6b 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3004,7 +3004,20 @@ getInvertibleOperands(const Operator *Op1,
   switch (Op1->getOpcode()) {
   default:
     break;
-  case Instruction::Add:
+  case Instruction::Or:
+    if (!cast<PossiblyDisjointInst>(Op1)->isDisjoint() ||
+        !cast<PossiblyDisjointInst>(Op2)->isDisjoint())
+      break;
+    [[fallthrough]];
+  case Instruction::Xor:
+  case Instruction::Add: {
+    Value *Other;
+    if (match(Op2, m_c_BinOp(m_Specific(Op1->getOperand(0)), m_Value(Other))))
+      return std::make_pair(Op1->getOperand(1), Other);
+    if (match(Op2, m_c_BinOp(m_Specific(Op1->getOperand(1)), m_Value(Other))))
+      return std::make_pair(Op1->getOperand(0), Other);
+    break;
+  }
   case Instruction::Sub:
     if (Op1->getOperand(0) == Op2->getOperand(0))
       return getOperands(1);
diff --git a/llvm/test/Transforms/InstSimplify/icmp.ll b/llvm/test/Transforms/InstSimplify/icmp.ll
index 3109768bdfe005..d1799098115496 100644
--- a/llvm/test/Transforms/InstSimplify/icmp.ll
+++ b/llvm/test/Transforms/InstSimplify/icmp.ll
@@ -270,7 +270,7 @@ define i1 @load_ptr(ptr %p) {
 
 define i1 @load_ptr_null_valid(ptr %p) null_pointer_is_valid {
 ; CHECK-LABEL: @load_ptr_null_valid(
-; CHECK-NEXT:    [[LOAD_P:%.*]] = load ptr, ptr [[P:%.*]], align 8, !dereferenceable !0
+; CHECK-NEXT:    [[LOAD_P:%.*]] = load ptr, ptr [[P:%.*]], align 8, !dereferenceable [[META0:![0-9]+]]
 ; CHECK-NEXT:    [[R:%.*]] = icmp ne ptr [[LOAD_P]], null
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
@@ -278,3 +278,81 @@ define i1 @load_ptr_null_valid(ptr %p) null_pointer_is_valid {
   %r = icmp ne ptr %load_p, null
   ret i1 %r
 }
+
+define i1 @non_eq_disjoint_or_common_op(i8 %x, i8 %y, i8 %ww, i8 %a) {
+; CHECK-LABEL: @non_eq_disjoint_or_common_op(
+; CHECK-NEXT:    ret i1 false
+;
+  %w = add nuw i8 %ww, 1
+  %z = add i8 %y, %w
+
+  %xy = or disjoint i8 %x, %y
+  %xz = or disjoint i8 %x, %z
+
+  %axy = add i8 %a, %xy
+  %axz = add i8 %a, %xz
+  %r = icmp eq i8 %axy, %axz
+  ret i1 %r
+}
+
+define i1 @non_eq_disjoint_or_common_op_fail(i8 %x, i8 %y, i8 %ww, i8 %a) {
+; CHECK-LABEL: @non_eq_disjoint_or_common_op_fail(
+; CHECK-NEXT:    [[W:%.*]] = add nuw i8 [[WW:%.*]], 1
+; CHECK-NEXT:    [[Z:%.*]] = add i8 [[Y:%.*]], [[W]]
+; CHECK-NEXT:    [[XY:%.*]] = or i8 [[X:%.*]], [[Y]]
+; CHECK-NEXT:    [[XZ:%.*]] = or disjoint i8 [[X]], [[Z]]
+; CHECK-NEXT:    [[AXY:%.*]] = add i8 [[A:%.*]], [[XY]]
+; CHECK-NEXT:    [[AXZ:%.*]] = add i8 [[A]], [[XZ]]
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[AXY]], [[AXZ]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %w = add nuw i8 %ww, 1
+  %z = add i8 %y, %w
+
+  %xy = or i8 %x, %y
+  %xz = or disjoint i8 %x, %z
+
+  %axy = add i8 %a, %xy
+  %axz = add i8 %a, %xz
+  %r = icmp eq i8 %axy, %axz
+  ret i1 %r
+}
+
+define i1 @non_eq_xor_common_op(i8 %x, i8 %y, i8 %ww, i8 %a) {
+; CHECK-LABEL: @non_eq_xor_common_op(
+; CHECK-NEXT:    ret i1 false
+;
+  %w = add nuw i8 %ww, 1
+  %z = add i8 %y, %w
+
+  %xy = xor i8 %y, %x
+  %xz = xor i8 %x, %z
+
+  %axy = add i8 %a, %xy
+  %axz = add i8 %a, %xz
+  %r = icmp eq i8 %axy, %axz
+  ret i1 %r
+}
+
+define i1 @non_eq_xor_common_op_fail(i8 %x, i8 %y, i8 %ww, i8 %a) {
+; CHECK-LABEL: @non_eq_xor_common_op_fail(
+; CHECK-NEXT:    [[W:%.*]] = add nsw i8 [[WW:%.*]], 1
+; CHECK-NEXT:    [[Z:%.*]] = add i8 [[Y:%.*]], [[W]]
+; CHECK-NEXT:    [[XY:%.*]] = xor i8 [[Y]], [[X:%.*]]
+; CHECK-NEXT:    [[XZ:%.*]] = xor i8 [[X]], [[Z]]
+; CHECK-NEXT:    [[AXY:%.*]] = add i8 [[A:%.*]], [[XY]]
+; CHECK-NEXT:    [[AXZ:%.*]] = add i8 [[A]], [[XZ]]
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[AXY]], [[AXZ]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %w = add nsw i8 %ww, 1
+  %z = add i8 %y, %w
+
+  %xy = xor i8 %y, %x
+  %xz = xor i8 %x, %z
+
+  %axy = add i8 %a, %xy
+  %axz = add i8 %a, %xz
+  %r = icmp eq i8 %axy, %axz
+  ret i1 %r
+}

[nikic]

LGTM