[InstCombine] Fold icmp spred (and X, highmask), C1 into icmp spred X, C2

[dtcxzyw]

Alive2: https://alive2.llvm.org/ce/z/Ffg64g
Closes #104772.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Yingwei Zheng (dtcxzyw)

Changes

Alive2: https://alive2.llvm.org/ce/z/Ffg64g
Closes #104772.

---

Full diff: https://github.com/llvm/llvm-project/pull/118197.diff

4 Files Affected:

• (modified) llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp (+11)
• (modified) llvm/test/Transforms/InstCombine/icmp-binop.ll (+107)
• (modified) llvm/test/Transforms/InstCombine/icmp.ll (+1-2)
• (modified) llvm/test/Transforms/InstCombine/pr17827.ll (+5-13)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index fed21db393ed22..58719737766837 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1760,6 +1760,17 @@ Instruction *InstCombinerImpl::foldICmpAndConstConst(ICmpInst &Cmp,
   if (!match(And, m_And(m_Value(X), m_APInt(C2))))
     return nullptr;
 
+  // (and X, highmask) s> [0, ~highmask] --> X s> ~highmask
+  if (Cmp.getPredicate() == ICmpInst::ICMP_SGT && C1.ule(~*C2) &&
+      C2->isNegatedPowerOf2())
+    return new ICmpInst(ICmpInst::ICMP_SGT, X,
+                        ConstantInt::get(X->getType(), ~*C2));
+  // (and X, highmask) s< [1, -highmask] --> X s< -highmask
+  if (Cmp.getPredicate() == ICmpInst::ICMP_SLT && !C1.isSignMask() &&
+      (C1 - 1).ule(~*C2) && C2->isNegatedPowerOf2() && !C2->isSignMask())
+    return new ICmpInst(ICmpInst::ICMP_SLT, X,
+                        ConstantInt::get(X->getType(), -*C2));
+
   // Don't perform the following transforms if the AND has multiple uses
   if (!And->hasOneUse())
     return nullptr;
diff --git a/llvm/test/Transforms/InstCombine/icmp-binop.ll b/llvm/test/Transforms/InstCombine/icmp-binop.ll
index 878f39bb7c9a56..356489716fff9b 100644
--- a/llvm/test/Transforms/InstCombine/icmp-binop.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-binop.ll
@@ -252,3 +252,110 @@ false:
   call void @use64(i64 %v)
   ret i1 false
 }
+
+define i1 @test_icmp_sgt_and_negpow2_zero(i32 %add) {
+; CHECK-LABEL: @test_icmp_sgt_and_negpow2_zero(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[ADD:%.*]], 7
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -8
+  %cmp = icmp sgt i32 %and, 0
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_slt_and_negpow2_one(i32 %add) {
+; CHECK-LABEL: @test_icmp_slt_and_negpow2_one(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[ADD:%.*]], 8
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -8
+  %cmp = icmp slt i32 %and, 1
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_sgt_and_negpow2_nonzero(i32 %add) {
+; CHECK-LABEL: @test_icmp_sgt_and_negpow2_nonzero(
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ADD:%.*]], -8
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[AND]], -2
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -8
+  %cmp = icmp sgt i32 %and, -2
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_sgt_and_nonnegpow2_zero(i32 %add) {
+; CHECK-LABEL: @test_icmp_sgt_and_nonnegpow2_zero(
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ADD:%.*]], 8
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[AND]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, 8
+  %cmp = icmp sgt i32 %and, 0
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_ult_and_negpow2_one(i32 %add) {
+; CHECK-LABEL: @test_icmp_ult_and_negpow2_one(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[ADD:%.*]], 8
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -8
+  %cmp = icmp ult i32 %and, 1
+  ret i1 %cmp
+}
+
+define i1 @test_imply_dom_condition(i32 %add) {
+; CHECK-LABEL: @test_imply_dom_condition(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[ADD:%.*]], 7
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    ret i1 false
+;
+  %and = and i32 %add, -8
+  %cmp = icmp sgt i32 %and, 0
+  tail call void @llvm.assume(i1 %cmp)
+  %min.iters.check = icmp ult i32 %and, 8
+  ret i1 %min.iters.check
+}
+
+define i1 @test_icmp_slt_and_negpow2_c(i32 %add) {
+; CHECK-LABEL: @test_icmp_slt_and_negpow2_c(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[ADD:%.*]], 32
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -32
+  %cmp = icmp slt i32 %and, 16
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_slt_and_negpow2_invalid_c(i32 %add) {
+; CHECK-LABEL: @test_icmp_slt_and_negpow2_invalid_c(
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ADD:%.*]], -32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[AND]], 48
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -32
+  %cmp = icmp slt i32 %and, 48
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_sgt_and_negpow2_c(i32 %add) {
+; CHECK-LABEL: @test_icmp_sgt_and_negpow2_c(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[ADD:%.*]], 31
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -32
+  %cmp = icmp sgt i32 %and, 16
+  ret i1 %cmp
+}
+
+define i1 @test_icmp_sgt_and_negpow2_invalid_c(i32 %add) {
+; CHECK-LABEL: @test_icmp_sgt_and_negpow2_invalid_c(
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ADD:%.*]], -32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[AND]], 48
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %and = and i32 %add, -32
+  %cmp = icmp sgt i32 %and, 48
+  ret i1 %cmp
+}
diff --git a/llvm/test/Transforms/InstCombine/icmp.ll b/llvm/test/Transforms/InstCombine/icmp.ll
index c1b9752607c3d4..b266d3e77c4344 100644
--- a/llvm/test/Transforms/InstCombine/icmp.ll
+++ b/llvm/test/Transforms/InstCombine/icmp.ll
@@ -2197,8 +2197,7 @@ define i1 @icmp_ashr_and_overshift(i8 %X) {
 
 define i1 @icmp_and_ashr_neg_and_legal(i8 %x) {
 ; CHECK-LABEL: @icmp_and_ashr_neg_and_legal(
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X:%.*]], -32
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[TMP1]], 16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 32
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %ashr = ashr i8 %x, 4
diff --git a/llvm/test/Transforms/InstCombine/pr17827.ll b/llvm/test/Transforms/InstCombine/pr17827.ll
index 2f10bb5c7f25f0..58b77ec60620e7 100644
--- a/llvm/test/Transforms/InstCombine/pr17827.ll
+++ b/llvm/test/Transforms/InstCombine/pr17827.ll
@@ -5,8 +5,7 @@
 define i1 @test_shift_and_cmp_not_changed1(i8 %p) {
 ; CHECK-LABEL: @test_shift_and_cmp_not_changed1(
 ; CHECK-NEXT:    [[SHLP:%.*]] = shl i8 [[P:%.*]], 5
-; CHECK-NEXT:    [[ANDP:%.*]] = and i8 [[SHLP]], -64
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[ANDP]], 32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[SHLP]], 64
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %shlp = shl i8 %p, 5
@@ -18,10 +17,7 @@ define i1 @test_shift_and_cmp_not_changed1(i8 %p) {
 ; With arithmetic right shift, the comparison should not be modified.
 define i1 @test_shift_and_cmp_not_changed2(i8 %p) {
 ; CHECK-LABEL: @test_shift_and_cmp_not_changed2(
-; CHECK-NEXT:    [[SHLP:%.*]] = ashr i8 [[P:%.*]], 5
-; CHECK-NEXT:    [[ANDP:%.*]] = and i8 [[SHLP]], -64
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[ANDP]], 32
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 true
 ;
   %shlp = ashr i8 %p, 5
   %andp = and i8 %shlp, -64
@@ -34,8 +30,7 @@ define i1 @test_shift_and_cmp_not_changed2(i8 %p) {
 define i1 @test_shift_and_cmp_changed1(i8 %p, i8 %q) {
 ; CHECK-LABEL: @test_shift_and_cmp_changed1(
 ; CHECK-NEXT:    [[ANDP:%.*]] = shl i8 [[P:%.*]], 5
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[ANDP]], -64
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[TMP1]], 32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[ANDP]], 33
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %andp = and i8 %p, 6
@@ -50,8 +45,7 @@ define i1 @test_shift_and_cmp_changed1(i8 %p, i8 %q) {
 define <2 x i1> @test_shift_and_cmp_changed1_vec(<2 x i8> %p, <2 x i8> %q) {
 ; CHECK-LABEL: @test_shift_and_cmp_changed1_vec(
 ; CHECK-NEXT:    [[ANDP:%.*]] = shl <2 x i8> [[P:%.*]], splat (i8 5)
-; CHECK-NEXT:    [[TMP1:%.*]] = and <2 x i8> [[ANDP]], splat (i8 -64)
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i8> [[TMP1]], splat (i8 32)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i8> [[ANDP]], splat (i8 33)
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %andp = and <2 x i8> %p, <i8 6, i8 6>
@@ -91,9 +85,7 @@ define <2 x i1> @test_shift_and_cmp_changed2_vec(<2 x i8> %p) {
 ; nsw on the shift should not affect the comparison.
 define i1 @test_shift_and_cmp_changed3(i8 %p) {
 ; CHECK-LABEL: @test_shift_and_cmp_changed3(
-; CHECK-NEXT:    [[SHLP:%.*]] = shl nsw i8 [[P:%.*]], 5
-; CHECK-NEXT:    [[ANDP:%.*]] = and i8 [[SHLP]], -64
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[ANDP]], 32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[P:%.*]], 2
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %shlp = shl nsw i8 %p, 5

[nikic]

LGTM