[llvm] [LVI] Generalize mask not equal conditions handling (PR #92946)
Antonio Frighetto via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 6 00:28:25 PDT 2024
https://github.com/antoniofrighetto updated https://github.com/llvm/llvm-project/pull/92946
>From c4593db2824e4941edc7f5c47d25353b3bf41270 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Thu, 6 Jun 2024 08:25:14 +0200
Subject: [PATCH 1/2] [LVI] Introduce test for PR92946 (NFC)
---
.../LazyValueAnalysis/lvi-icmp-ne-of-and.ll | 76 +++++++++++++++++++
.../CorrelatedValuePropagation/icmp.ll | 40 +++++++++-
2 files changed, 115 insertions(+), 1 deletion(-)
create mode 100644 llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll
diff --git a/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll b/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll
new file mode 100644
index 0000000000000..ce53c8059f1ae
--- /dev/null
+++ b/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll
@@ -0,0 +1,76 @@
+; RUN: opt < %s -passes="jump-threading,print<lazy-value-info>" -disable-output 2>&1 | FileCheck %s
+
+; (Val & 4) != 4, ctr_z(M) <= ctr_z(C), sat
+define i1 @test(i4 noundef %arg) {
+entry:
+ %mask = and i4 %arg, 4
+ %cmp = icmp ne i4 %mask, 4
+ br i1 %cmp, label %l_true, label %l_false
+
+; CHECK-LABEL: l_true:
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+l_true:
+ ret i1 1
+l_false:
+ ret i1 0
+}
+
+; (Val & 5) != 4, ctr_z(M) <= ctr_z(C), sat
+define i1 @test_2(i4 noundef %arg) {
+entry:
+ %mask = and i4 %arg, 5
+ %cmp = icmp ne i4 %mask, 4
+ br i1 %cmp, label %l_true, label %l_false
+
+; CHECK-LABEL: l_true:
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+l_true:
+ ret i1 1
+l_false:
+ ret i1 0
+}
+
+; (Val & 6) != 4, ctr_z(M) <= ctr_z(C), sat
+define i1 @test_3(i4 noundef %arg) {
+entry:
+ %mask = and i4 %arg, 6
+ %cmp = icmp ne i4 %mask, 4
+ br i1 %cmp, label %l_true, label %l_false
+
+; CHECK-LABEL: l_true:
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+l_true:
+ ret i1 1
+l_false:
+ ret i1 0
+}
+
+; (Val & 8) != 4, !ctr_z(M) <= ctr_z(C), unsat
+define i1 @test_4(i4 noundef %arg) {
+entry:
+ %mask = and i4 %arg, 8
+ %cmp = icmp ne i4 %mask, 4
+ br i1 %cmp, label %l_true, label %l_false
+
+; CHECK-LABEL: l_true:
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+l_true:
+ ret i1 1
+l_false:
+ ret i1 0
+}
+
+; (Val & 8) != 16, ctr_z(M) <= ctr_z(C), !(M >u C), unsat
+define i1 @test_5(i8 noundef %arg) {
+entry:
+ %mask = and i8 %arg, 8
+ %cmp = icmp ne i8 %mask, 16
+ br i1 %cmp, label %l_true, label %l_false
+
+; CHECK-LABEL: l_true:
+; CHECK-NEXT: ; LatticeVal for: 'i8 %arg' is: overdefined
+l_true:
+ ret i1 1
+l_false:
+ ret i1 0
+}
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
index b5337b9ddc248..475ebbb923b42 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -595,7 +595,7 @@ define i1 @test_assume_cmp_with_offset_or(i64 %idx, i1 %other) {
; CHECK: T:
; CHECK-NEXT: ret i1 true
; CHECK: F:
-; CHECK-NEXT: ret i1 [[CMP2:%.*]]
+; CHECK-NEXT: ret i1 [[OTHER:%.*]]
;
%idx.off1 = or disjoint i64 %idx, 5
%cmp1 = icmp ugt i64 %idx.off1, 10
@@ -1475,3 +1475,41 @@ entry:
%select = select i1 %cmp1, i1 %cmp2, i1 false
ret i1 %select
}
+
+declare void @opaque()
+
+define void @test_icmp_ne_from_implied_range(i32 noundef %arg) {
+; CHECK-LABEL: @test_icmp_ne_from_implied_range(
+; CHECK-NEXT: [[AND_MASK:%.*]] = and i32 [[ARG:%.*]], -8
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND_MASK]], -16
+; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[ELSE:%.*]]
+; CHECK: else:
+; CHECK-NEXT: switch i32 [[ARG]], label [[END]] [
+; CHECK-NEXT: i32 -16, label [[SW_CASE:%.*]]
+; CHECK-NEXT: i32 -12, label [[SW_CASE]]
+; CHECK-NEXT: i32 -9, label [[SW_CASE]]
+; CHECK-NEXT: ]
+; CHECK: sw.case:
+; CHECK-NEXT: call void @opaque()
+; CHECK-NEXT: br label [[END]]
+; CHECK: end:
+; CHECK-NEXT: ret void
+;
+ %and.mask = and i32 %arg, -8
+ %cmp = icmp eq i32 %and.mask, -16
+ br i1 %cmp, label %end, label %else
+
+else:
+ switch i32 %arg, label %end [
+ i32 -16, label %sw.case
+ i32 -12, label %sw.case
+ i32 -9, label %sw.case
+ ]
+
+sw.case:
+ call void @opaque()
+ br label %end
+
+end:
+ ret void
+}
>From ae24e1f6ee56565d7d960e97ca0b17485113bae2 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Thu, 6 Jun 2024 08:26:40 +0200
Subject: [PATCH 2/2] [LVI] Generalize mask not equal conditions handling
Extend `V & Mask != 0` for non-zero constants, when retrieving
constraint value information from a non-equality comparison.
Proofs: https://alive2.llvm.org/ce/z/PNDN3K.
Motivating example: https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/gcc.dg/tree-ssa/vrp76.c.
---
llvm/lib/Analysis/LazyValueInfo.cpp | 25 ++++++++++++++-----
.../LazyValueAnalysis/lvi-icmp-ne-of-and.ll | 6 ++---
.../CorrelatedValuePropagation/icmp.ll | 6 +----
3 files changed, 23 insertions(+), 14 deletions(-)
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 6cded828c25f4..5e1b48900c327 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1191,12 +1191,25 @@ std::optional<ValueLatticeElement> LazyValueInfoImpl::getValueFromICmpCondition(
return ValueLatticeElement::getRange(
ConstantRange::fromKnownBits(Known, /*IsSigned*/ false));
}
- // If (Val & Mask) != 0 then the value must be larger than the lowest set
- // bit of Mask.
- if (EdgePred == ICmpInst::ICMP_NE && !Mask->isZero() && C->isZero()) {
- return ValueLatticeElement::getRange(ConstantRange::getNonEmpty(
- APInt::getOneBitSet(BitWidth, Mask->countr_zero()),
- APInt::getZero(BitWidth)));
+
+ if (EdgePred == ICmpInst::ICMP_NE && !Mask->isZero()) {
+ // If (Val & Mask) != 0 then the value must be larger than the lowest set
+ // bit of Mask.
+ unsigned TrailingZeroesMask = Mask->countr_zero();
+ if (C->isZero())
+ return ValueLatticeElement::getRange(ConstantRange::getNonEmpty(
+ APInt::getOneBitSet(BitWidth, TrailingZeroesMask),
+ APInt::getZero(BitWidth)));
+
+ unsigned TrailingZeroesC = C->countr_zero();
+ // If (Val & Mask) != C, where Mask >=u C and the number of trailing zeroes
+ // of Mask is at most equal to the number of trailing zeroes of C, then
+ // the value must be larger than the lowest set bit of Mask, offset by
+ // constant C.
+ if (Mask->uge(*C) && TrailingZeroesMask <= TrailingZeroesC) {
+ return ValueLatticeElement::getRange(ConstantRange::getNonEmpty(
+ APInt::getOneBitSet(BitWidth, TrailingZeroesMask) + *C, *C));
+ }
}
}
diff --git a/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll b/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll
index ce53c8059f1ae..7f73715961b44 100644
--- a/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll
+++ b/llvm/test/Analysis/LazyValueAnalysis/lvi-icmp-ne-of-and.ll
@@ -8,7 +8,7 @@ entry:
br i1 %cmp, label %l_true, label %l_false
; CHECK-LABEL: l_true:
-; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: constantrange<-8, 4>
l_true:
ret i1 1
l_false:
@@ -23,7 +23,7 @@ entry:
br i1 %cmp, label %l_true, label %l_false
; CHECK-LABEL: l_true:
-; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: constantrange<5, 4>
l_true:
ret i1 1
l_false:
@@ -38,7 +38,7 @@ entry:
br i1 %cmp, label %l_true, label %l_false
; CHECK-LABEL: l_true:
-; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: overdefined
+; CHECK-NEXT: ; LatticeVal for: 'i4 %arg' is: constantrange<6, 4>
l_true:
ret i1 1
l_false:
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
index 475ebbb923b42..8733979dc339f 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -1484,11 +1484,7 @@ define void @test_icmp_ne_from_implied_range(i32 noundef %arg) {
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND_MASK]], -16
; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[ELSE:%.*]]
; CHECK: else:
-; CHECK-NEXT: switch i32 [[ARG]], label [[END]] [
-; CHECK-NEXT: i32 -16, label [[SW_CASE:%.*]]
-; CHECK-NEXT: i32 -12, label [[SW_CASE]]
-; CHECK-NEXT: i32 -9, label [[SW_CASE]]
-; CHECK-NEXT: ]
+; CHECK-NEXT: br label [[END]]
; CHECK: sw.case:
; CHECK-NEXT: call void @opaque()
; CHECK-NEXT: br label [[END]]
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