[InstCombine] Simplify compare abs(X) and X. #76385

Z572 · 2023-12-26T07:52:03Z

fix #72653
proof: https://alive2.llvm.org/ce/z/LZzZaj

llvmbot · 2023-12-26T07:52:29Z

@llvm/pr-subscribers-llvm-transforms

Author: None (Z572)

Changes

fix #72653
proof: https://alive2.llvm.org/ce/z/zPNyUb

Full diff: https://github.com/llvm/llvm-project/pull/76385.diff

2 Files Affected:

(modified) llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp (+41)
(added) llvm/test/Transforms/InstCombine/icmp-abs.ll (+212)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 289976718e52f3..19ddffe75ff9b6 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -7109,6 +7109,47 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
     }
   }
 
+  {
+    Value *X;
+    Constant *C;
+    if (match(Op0, m_OneUse(m_Intrinsic<Intrinsic::abs>(m_Value(X),
+                                                        m_Constant(C)))) &&
+        match(Op1, m_Specific(X))) {
+      auto *NullValue = Constant::getNullValue(X->getType());
+      auto *MinVal = ConstantInt::get(
+          X->getType(),
+          APInt::getSignedMinValue(X->getType()->getScalarSizeInBits()));
+      bool IsIntMinPosion = C->isZeroValue();
+      switch (Pred) {
+      case CmpInst::ICMP_ULE:
+      case CmpInst::ICMP_SGE:
+        return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
+      case CmpInst::ICMP_UGT:
+      case CmpInst::ICMP_SLT:
+        return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
+      case CmpInst::ICMP_UGE:
+      case CmpInst::ICMP_SLE:
+      case CmpInst::ICMP_EQ: {
+        auto *SGE = Builder.CreateICmpSGE(X, NullValue);
+        return replaceInstUsesWith(
+            I, IsIntMinPosion
+                   ? Builder.CreateOr(SGE, Builder.CreateICmpEQ(X, MinVal))
+                   : SGE);
+      }
+      case CmpInst::ICMP_ULT:
+      case CmpInst::ICMP_NE:
+      case CmpInst::ICMP_SGT: {
+        auto *SLT = Builder.CreateICmpSLT(X, NullValue);
+        return replaceInstUsesWith(
+            I, IsIntMinPosion
+                   ? Builder.CreateAnd(SLT, Builder.CreateICmpNE(X, MinVal))
+                   : SLT);
+      }
+      default:
+        break;
+      }
+    }
+  }
   if (Instruction *Res = foldICmpEquality(I))
     return Res;
 
diff --git a/llvm/test/Transforms/InstCombine/icmp-abs.ll b/llvm/test/Transforms/InstCombine/icmp-abs.ll
new file mode 100644
index 00000000000000..382dab800dd942
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/icmp-abs.ll
@@ -0,0 +1,212 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-p1:16:16:16-p2:32:32:32-p3:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+declare i4 @llvm.abs.i4(i4, i1)
+declare void @use_i4(i4)
+
+define i1 @icmp_sge_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_sge_abs(
+; CHECK-NEXT:    ret i1 true
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp sge i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_sge_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_sge_abs_false(
+; CHECK-NEXT:    ret i1 true
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp sge i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_eq_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_eq_abs(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i4 [[ARG:%.*]], -1
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp eq i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_eq_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_eq_abs_false(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i4 [[ARG:%.*]], -7
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp eq i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ne_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_ne_abs(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i4 [[ARG:%.*]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp ne i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ne_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_ne_abs_false(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i4 [[ARG:%.*]], -8
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp ne i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_sle_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_sle_abs(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i4 [[ARG:%.*]], -1
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp sle i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_sle_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_sle_abs_false(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i4 [[ARG:%.*]], -7
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp sle i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_slt_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_slt_abs(
+; CHECK-NEXT:    ret i1 false
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp slt i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_slt_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_slt_abs_false(
+; CHECK-NEXT:    ret i1 false
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp slt i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_sgt_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_sgt_abs(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i4 [[ARG:%.*]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp sgt i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_sgt_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_sgt_abs_false(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i4 [[ARG:%.*]], -8
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp sgt i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ugt_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_ugt_abs(
+; CHECK-NEXT:    ret i1 false
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp ugt i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ugt_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_ugt_abs_false(
+; CHECK-NEXT:    ret i1 false
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp ugt i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_uge_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_uge_abs(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i4 [[ARG:%.*]], -1
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp uge i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_uge_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_uge_abs_false(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i4 [[ARG:%.*]], -7
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp uge i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ule_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_ule_abs(
+; CHECK-NEXT:    ret i1 true
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp ule i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ule_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_ule_abs_false(
+; CHECK-NEXT:    ret i1 true
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp ule i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ult_abs(i4 %arg) {
+; CHECK-LABEL: @icmp_ult_abs(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i4 [[ARG:%.*]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 true)
+  %cmp = icmp ult i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_ult_abs_false(i4 %arg) {
+; CHECK-LABEL: @icmp_ult_abs_false(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i4 [[ARG:%.*]], -8
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp ult i4 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @icmp_sgt_abs_use(i4 %arg) {
+; CHECK-LABEL: @icmp_sgt_abs_use(
+; CHECK-NEXT:    [[ABS:%.*]] = call i4 @llvm.abs.i4(i4 [[ARG:%.*]], i1 false)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i4 [[ABS]], [[ARG]]
+; CHECK-NEXT:    call void @use_i4(i4 [[ABS]])
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = call i4 @llvm.abs.i4(i4 %arg, i1 false)
+  %cmp = icmp sgt i4 %abs, %arg
+  call void @use_i4(i4 %abs)
+  ret i1 %cmp
+}

dtcxzyw · 2023-12-26T07:55:20Z

See also #73189.

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

llvm/test/Transforms/InstCombine/icmp-abs.ll

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

nikic · 2024-01-02T15:17:29Z

Please rebase over 9d5b096 and move the fold into foldICmpCommutative().

proof: https://alive2.llvm.org/ce/z/LZzZaj

dtcxzyw

LGTM. Please wait for additional approval from other reviewers.

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

llvm/test/Transforms/InstCombine/icmp-abs.ll

PR Link: llvm/llvm-project#76385

dtcxzyw

LGTM. Please wait for additional approval from other reviewers.

nikic

LGTM

Z572 requested a review from nikic as a code owner December 26, 2023 07:52

llvmbot added the llvm:transforms label Dec 26, 2023

dtcxzyw requested a review from fhahn December 26, 2023 07:55

dtcxzyw requested changes Dec 29, 2023

View reviewed changes

Z572 force-pushed the patch-7 branch from 5f80b27 to e48ff3d Compare December 29, 2023 17:49

nikic reviewed Jan 2, 2024

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llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp Outdated Show resolved Hide resolved

Z572 force-pushed the patch-7 branch from e48ff3d to d09b48a Compare January 2, 2024 12:19

[InstCombine] Simplify compare abs(X) and X.

26debb2

proof: https://alive2.llvm.org/ce/z/LZzZaj

Z572 force-pushed the patch-7 branch from d09b48a to 26debb2 Compare January 2, 2024 16:19

dtcxzyw approved these changes Jan 4, 2024

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llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp Outdated Show resolved Hide resolved

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp Outdated Show resolved Hide resolved

llvm/test/Transforms/InstCombine/icmp-abs.ll Show resolved Hide resolved

dtcxzyw added a commit to dtcxzyw/llvm-opt-benchmark that referenced this pull request Jan 4, 2024

pre-commit: test PR76385

2c00a09

PR Link: llvm/llvm-project#76385

dtcxzyw mentioned this pull request Jan 4, 2024

pre-commit: test PR76385 dtcxzyw/llvm-opt-benchmark#95

Closed

fixup! [InstCombine] Simplify compare abs(X) and X.

229ed58

dtcxzyw approved these changes Jan 5, 2024

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nikic approved these changes Jan 5, 2024

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Z572 merged commit 86ef039 into llvm:main Jan 5, 2024

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