[llvm] d0d12fc - [InstCombine] Fold (X==Z) ? (Y==Z) : (!(Y==Z) && X==Y) --> X==Y (#108619)
via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 3 07:33:33 PDT 2024
Author: Marina Taylor
Date: 2024-10-03T15:33:30+01:00
New Revision: d0d12fc78a3c552e6bf4158825d4917645911f6e
URL: https://github.com/llvm/llvm-project/commit/d0d12fc78a3c552e6bf4158825d4917645911f6e
DIFF: https://github.com/llvm/llvm-project/commit/d0d12fc78a3c552e6bf4158825d4917645911f6e.diff
LOG: [InstCombine] Fold (X==Z) ? (Y==Z) : (!(Y==Z) && X==Y) --> X==Y (#108619)
This corresponds to the canonicalized form of some logic that was
seen in Swift-generated code for comparing optional pointers:
`(X==Z || Y==Z) ? (X==Z && Y==Z) : X==Y --> X==Y`
where `Z` was the constant `0`.
https://alive2.llvm.org/ce/z/J_3aa9
Added:
llvm/test/Transforms/InstCombine/icmp-equality-test.ll
Modified:
llvm/lib/Transforms/InstCombine/InstCombineInternal.h
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index da6f991ad4cd15..7c6f42de77fc71 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -739,6 +739,7 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
Instruction *foldSelectOfBools(SelectInst &SI);
Instruction *foldSelectToCmp(SelectInst &SI);
Instruction *foldSelectExtConst(SelectInst &Sel);
+ Instruction *foldSelectEqualityTest(SelectInst &SI);
Instruction *foldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI);
Instruction *foldSelectIntoOp(SelectInst &SI, Value *, Value *);
Instruction *foldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 3dbe95897d6356..3f780285efe423 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1410,6 +1410,44 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
return nullptr;
}
+/// Fold the following code sequence:
+/// \code
+/// %XeqZ = icmp eq i64 %X, %Z
+/// %YeqZ = icmp eq i64 %Y, %Z
+/// %XeqY = icmp eq i64 %X, %Y
+/// %not.YeqZ = xor i1 %YeqZ, true
+/// %and = select i1 %not.YeqZ, i1 %XeqY, i1 false
+/// %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+/// \code
+///
+/// into:
+/// %equal = icmp eq i64 %X, %Y
+Instruction *InstCombinerImpl::foldSelectEqualityTest(SelectInst &Sel) {
+ Value *X, *Y, *Z;
+ Value *XeqY, *XeqZ = Sel.getCondition(), *YeqZ = Sel.getTrueValue();
+
+ if (!match(XeqZ, m_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(X), m_Value(Z))))
+ return nullptr;
+
+ if (!match(YeqZ,
+ m_c_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(Y), m_Specific(Z))))
+ std::swap(X, Z);
+
+ if (!match(YeqZ,
+ m_c_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(Y), m_Specific(Z))))
+ return nullptr;
+
+ if (!match(Sel.getFalseValue(),
+ m_c_LogicalAnd(m_Not(m_Specific(YeqZ)), m_Value(XeqY))))
+ return nullptr;
+
+ if (!match(XeqY,
+ m_c_SpecificICmp(ICmpInst::ICMP_EQ, m_Specific(X), m_Specific(Y))))
+ return nullptr;
+
+ return replaceInstUsesWith(Sel, XeqY);
+}
+
// See if this is a pattern like:
// %old_cmp1 = icmp slt i32 %x, C2
// %old_replacement = select i1 %old_cmp1, i32 %target_low, i32 %target_high
@@ -4112,6 +4150,9 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
if (Instruction *I = foldSelectToCmp(SI))
return I;
+ if (Instruction *I = foldSelectEqualityTest(SI))
+ return I;
+
// Fold:
// (select A && B, T, F) -> (select A, (select B, T, F), F)
// (select A || B, T, F) -> (select A, T, (select B, T, F))
diff --git a/llvm/test/Transforms/InstCombine/icmp-equality-test.ll b/llvm/test/Transforms/InstCombine/icmp-equality-test.ll
new file mode 100644
index 00000000000000..c2740ca7fe8aa9
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/icmp-equality-test.ll
@@ -0,0 +1,229 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @icmp_equality_test(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+entry:
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, %Y
+ %not.YeqZ = xor i1 %YeqZ, true
+ %and = select i1 %not.YeqZ, i1 %XeqY, i1 false
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_constant(i42 %X, i42 %Y) {
+; CHECK-LABEL: @icmp_equality_test_constant(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i42 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+entry:
+ %XeqC = icmp eq i42 %X, -42
+ %YeqC = icmp eq i42 %Y, -42
+ %XeqY = icmp eq i42 %X, %Y
+ %not.YeqC = xor i1 %YeqC, true
+ %and = select i1 %not.YeqC, i1 %XeqY, i1 false
+ %equal = select i1 %XeqC, i1 %YeqC, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_swift_optional_pointers(i64 %X, i64 %Y) {
+; CHECK-LABEL: @icmp_equality_test_swift_optional_pointers(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+entry:
+ %XeqC = icmp eq i64 %X, 0
+ %YeqC = icmp eq i64 %Y, 0
+ %either = select i1 %XeqC, i1 true, i1 %YeqC
+ %both = select i1 %XeqC, i1 %YeqC, i1 false
+ %XeqY = icmp eq i64 %X, %Y
+ %equal = select i1 %either, i1 %both, i1 %XeqY
+ ret i1 %equal
+}
+
+define <2 x i1> @icmp_equality_test_vector(<2 x i64> %X, <2 x i64> %Y) {
+; CHECK-LABEL: @icmp_equality_test_vector(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq <2 x i64> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[XEQY]]
+;
+entry:
+ %XeqC = icmp eq <2 x i64> %X, <i64 123, i64 456>
+ %YeqC = icmp eq <2 x i64> %Y, <i64 123, i64 456>
+ %XeqY = icmp eq <2 x i64> %X, %Y
+ %not.YeqC = xor <2 x i1> %YeqC, <i1 true, i1 true>
+ %and = select <2 x i1> %not.YeqC, <2 x i1> %XeqY, <2 x i1> <i1 false, i1 false>
+ %equal = select <2 x i1> %XeqC, <2 x i1> %YeqC, <2 x i1> %and
+ ret <2 x i1> %equal
+}
+
+define i1 @icmp_equality_test_commute_icmp1(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_commute_icmp1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+entry:
+ %XeqZ = icmp eq i64 %Z, %X
+ %YeqZ = icmp eq i64 %Z, %Y
+ %XeqY = icmp eq i64 %Y, %X
+ %not.YeqZ = xor i1 %YeqZ, true
+ %and = select i1 %not.YeqZ, i1 %XeqY, i1 false
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_commute_icmp2(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_commute_icmp2(
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+ %XeqZ = icmp eq i64 %Z, %X
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %Y, %X
+ %not.YeqZ = xor i1 %YeqZ, true
+ %and = select i1 %not.YeqZ, i1 %XeqY, i1 false
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_commute_select1(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_commute_select1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+entry:
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, %Y
+ %and = select i1 %YeqZ, i1 false, i1 %XeqY
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_commute_select2(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_commute_select2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: ret i1 [[XEQY]]
+;
+entry:
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, %Y
+ %not.XeqZ = xor i1 %XeqZ, true
+ %and = select i1 %YeqZ, i1 false, i1 %XeqY
+ %equal = select i1 %not.XeqZ, i1 %and, i1 %YeqZ
+ ret i1 %equal
+}
+
+; Negative tests below
+
+define i1 @icmp_equality_test_wrong_constant(i64 %X, i64 %Y) {
+; CHECK-LABEL: @icmp_equality_test_wrong_constant(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQC:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT: [[YEQC:%.*]] = icmp eq i64 [[Y:%.*]], 999
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X]], [[Y]]
+; CHECK-NEXT: [[NOT_YEQC:%.*]] = xor i1 [[YEQC]], true
+; CHECK-NEXT: [[AND:%.*]] = select i1 [[NOT_YEQC]], i1 [[XEQY]], i1 false
+; CHECK-NEXT: [[EQUAL:%.*]] = select i1 [[XEQC]], i1 [[YEQC]], i1 [[AND]]
+; CHECK-NEXT: ret i1 [[EQUAL]]
+;
+entry:
+ %XeqC = icmp eq i64 %X, 0
+ %YeqC = icmp eq i64 %Y, 999
+ %XeqY = icmp eq i64 %X, %Y
+ %not.YeqC = xor i1 %YeqC, true
+ %and = select i1 %not.YeqC, i1 %XeqY, i1 false
+ %equal = select i1 %XeqC, i1 %YeqC, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_missing_not(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_missing_not(
+; CHECK-NEXT: [[XEQZ:%.*]] = icmp eq i64 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT: [[YEQZ:%.*]] = icmp eq i64 [[Y:%.*]], [[Z]]
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X]], [[Y]]
+; CHECK-NEXT: [[AND:%.*]] = select i1 [[YEQZ]], i1 [[XEQY]], i1 false
+; CHECK-NEXT: [[EQUAL:%.*]] = select i1 [[XEQZ]], i1 [[YEQZ]], i1 [[AND]]
+; CHECK-NEXT: ret i1 [[EQUAL]]
+;
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, %Y
+ %and = select i1 %YeqZ, i1 %XeqY, i1 false
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_wrong_and(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_wrong_and(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQZ:%.*]] = icmp eq i64 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT: [[YEQZ:%.*]] = icmp eq i64 [[Y:%.*]], [[Z]]
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X]], [[Y]]
+; CHECK-NEXT: [[AND:%.*]] = select i1 [[YEQZ]], i1 [[XEQY]], i1 false
+; CHECK-NEXT: [[EQUAL:%.*]] = select i1 [[XEQZ]], i1 [[YEQZ]], i1 [[AND]]
+; CHECK-NEXT: ret i1 [[EQUAL]]
+;
+entry:
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, %Y
+ %not.YeqZ = xor i1 %YeqZ, true
+ %and = select i1 %not.YeqZ, i1 false, i1 %XeqY
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_wrong_cmp(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_wrong_cmp(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQZ:%.*]] = icmp eq i64 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT: [[YEQZ:%.*]] = icmp eq i64 [[Y:%.*]], [[Z]]
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X]], 999
+; CHECK-NEXT: [[NOT_YEQZ:%.*]] = xor i1 [[YEQZ]], true
+; CHECK-NEXT: [[AND:%.*]] = select i1 [[NOT_YEQZ]], i1 [[XEQY]], i1 false
+; CHECK-NEXT: [[EQUAL:%.*]] = select i1 [[XEQZ]], i1 [[YEQZ]], i1 [[AND]]
+; CHECK-NEXT: ret i1 [[EQUAL]]
+;
+entry:
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, 999
+ %not.YeqZ = xor i1 %YeqZ, true
+ %and = select i1 %not.YeqZ, i1 %XeqY, i1 false
+ %equal = select i1 %XeqZ, i1 %YeqZ, i1 %and
+ ret i1 %equal
+}
+
+define i1 @icmp_equality_test_wrong_equal(i64 %X, i64 %Y, i64 %Z) {
+; CHECK-LABEL: @icmp_equality_test_wrong_equal(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[XEQZ:%.*]] = icmp eq i64 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT: [[YEQZ:%.*]] = icmp eq i64 [[Y:%.*]], [[Z]]
+; CHECK-NEXT: [[XEQY:%.*]] = icmp eq i64 [[X]], [[Y]]
+; CHECK-NEXT: [[NOT_YEQZ:%.*]] = xor i1 [[YEQZ]], true
+; CHECK-NEXT: [[AND:%.*]] = select i1 [[NOT_YEQZ]], i1 [[XEQY]], i1 false
+; CHECK-NEXT: [[EQUAL:%.*]] = select i1 [[XEQZ]], i1 [[AND]], i1 [[YEQZ]]
+; CHECK-NEXT: ret i1 [[EQUAL]]
+;
+entry:
+ %XeqZ = icmp eq i64 %X, %Z
+ %YeqZ = icmp eq i64 %Y, %Z
+ %XeqY = icmp eq i64 %X, %Y
+ %not.YeqZ = xor i1 %YeqZ, true
+ %and = select i1 %not.YeqZ, i1 %XeqY, i1 false
+ %equal = select i1 %XeqZ, i1 %and, i1 %YeqZ
+ ret i1 %equal
+}
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