[llvm] [CVP]: Fold `icmp eq X, C` to `trunc X to i1` if C=2k+1 and X in [2k, 2k+1] (PR #83829)
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Mon Mar 4 03:45:13 PST 2024
https://github.com/YanWQ-monad updated https://github.com/llvm/llvm-project/pull/83829
>From 411ab902867d158304ababe1f645d85ba120ca19 Mon Sep 17 00:00:00 2001
From: YanWQ-monad <YanWQmonad at gmail.com>
Date: Mon, 4 Mar 2024 19:23:02 +0800
Subject: [PATCH 1/3] [CVP]: Add tests from rust-lang/rust#121673
---
.../CorrelatedValuePropagation/icmp.ll | 60 +++++++++++++++++++
1 file changed, 60 insertions(+)
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
index 101820a4c65f23..2dde67e274884e 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -1455,3 +1455,63 @@ entry:
%select = select i1 %cmp1, i1 %cmp2, i1 false
ret i1 %select
}
+
+define i1 @test_icmp_eq_on_valid_bool_range(i8 %x) {
+; CHECK-LABEL: @test_icmp_eq_on_valid_bool_range(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i8 [[X:%.*]], 2
+; CHECK-NEXT: br i1 [[TMP1]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK: bb2:
+; CHECK-NEXT: [[TMP2:%.*]] = tail call i1 @get_bool()
+; CHECK-NEXT: br label [[BB3:%.*]]
+; CHECK: bb1:
+; CHECK-NEXT: [[TMP3:%.*]] = icmp eq i8 [[X]], 1
+; CHECK-NEXT: br label [[BB3]]
+; CHECK: bb3:
+; CHECK-NEXT: [[TMP4:%.*]] = phi i1 [ [[TMP3]], [[BB1]] ], [ [[TMP2]], [[BB2]] ]
+; CHECK-NEXT: ret i1 [[TMP4]]
+;
+ %1 = icmp ult i8 %x, 2
+ br i1 %1, label %bb1, label %bb2
+
+bb2:
+ %2 = tail call i1 @get_bool()
+ br label %bb3
+
+bb1:
+ %3 = icmp eq i8 %x, 1
+ br label %bb3
+
+bb3:
+ %4 = phi i1 [ %3, %bb1 ], [ %2, %bb2 ]
+ ret i1 %4
+}
+
+define i1 @test_icmp_ne_on_valid_bool_range(i8 %x) {
+; CHECK-LABEL: @test_icmp_ne_on_valid_bool_range(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i8 [[X:%.*]], 2
+; CHECK-NEXT: br i1 [[TMP1]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK: bb2:
+; CHECK-NEXT: [[TMP2:%.*]] = tail call i1 @get_bool()
+; CHECK-NEXT: br label [[BB3:%.*]]
+; CHECK: bb1:
+; CHECK-NEXT: [[TMP3:%.*]] = icmp ne i8 [[X]], 0
+; CHECK-NEXT: br label [[BB3]]
+; CHECK: bb3:
+; CHECK-NEXT: [[TMP4:%.*]] = phi i1 [ [[TMP3]], [[BB1]] ], [ [[TMP2]], [[BB2]] ]
+; CHECK-NEXT: ret i1 [[TMP4]]
+;
+ %1 = icmp ult i8 %x, 2
+ br i1 %1, label %bb1, label %bb2
+
+bb2:
+ %2 = tail call i1 @get_bool()
+ br label %bb3
+
+bb1:
+ %3 = icmp ne i8 %x, 0
+ br label %bb3
+
+bb3:
+ %4 = phi i1 [ %3, %bb1 ], [ %2, %bb2 ]
+ ret i1 %4
+}
>From 2aea11f5bb6490099af4ee630d287e61c763b4a1 Mon Sep 17 00:00:00 2001
From: YanWQ-monad <YanWQmonad at gmail.com>
Date: Mon, 4 Mar 2024 19:30:14 +0800
Subject: [PATCH 2/3] [CVP]: Fold `icmp eq X, C` to `trunc X to i1` if C=2k+1
and X in [2k, 2k+1]
---
.../Scalar/CorrelatedValuePropagation.cpp | 36 +++++++++++++++++++
.../CorrelatedValuePropagation/icmp.ll | 8 ++---
llvm/test/Transforms/JumpThreading/pr33917.ll | 8 ++---
3 files changed, 44 insertions(+), 8 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 490cb7e528eb6f..73be5f0b016603 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -332,6 +332,39 @@ static bool constantFoldCmp(CmpInst *Cmp, LazyValueInfo *LVI) {
return true;
}
+/// Given an icmp `icmp eq X, C`,
+/// if we already know that C is 2k+1 and X is in [2k, 2k+1],
+/// then we can fold it to `trunc X to i1`.
+static bool processEqualityICmp(CmpInst *Cmp, LazyValueInfo *LVI) {
+ if (Cmp->getType()->isVectorTy() ||
+ !Cmp->getOperand(0)->getType()->isIntegerTy() || !Cmp->isEquality())
+ return false;
+
+ Value *Op0 = Cmp->getOperand(0);
+ Value *Op1 = Cmp->getOperand(1);
+ ConstantInt *CI = dyn_cast<ConstantInt>(Op1);
+ if (!CI)
+ return false;
+
+ ConstantRange Range =
+ LVI->getConstantRangeAtUse(Cmp->getOperandUse(0), /*UndefAllowed*/ true);
+ APInt RangeSize = Range.getUpper() - Range.getLower();
+ APInt Value = CI->getValue();
+ if (RangeSize != 2 || !Range.contains(Value))
+ return false;
+
+ bool ShouldBeOdd = Cmp->getPredicate() == ICmpInst::Predicate::ICMP_EQ;
+ if ((CI->getValue() & 1) == ShouldBeOdd) {
+ IRBuilder<> B{Cmp};
+ auto *Trunc = B.CreateTruncOrBitCast(Op0, Cmp->getType());
+ Cmp->replaceAllUsesWith(Trunc);
+ Cmp->eraseFromParent();
+ return true;
+ }
+
+ return false;
+}
+
static bool processCmp(CmpInst *Cmp, LazyValueInfo *LVI) {
if (constantFoldCmp(Cmp, LVI))
return true;
@@ -340,6 +373,9 @@ static bool processCmp(CmpInst *Cmp, LazyValueInfo *LVI) {
if (processICmp(ICmp, LVI))
return true;
+ if (processEqualityICmp(Cmp, LVI))
+ return true;
+
return false;
}
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
index 2dde67e274884e..ccfbc274d570ce 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -594,10 +594,10 @@ define void @test_cmp_phi(i8 %a) {
; CHECK-NEXT: br i1 [[C0]], label [[LOOP:%.*]], label [[EXIT:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[P:%.*]] = phi i8 [ [[A]], [[ENTRY:%.*]] ], [ [[B:%.*]], [[LOOP]] ]
-; CHECK-NEXT: [[C1:%.*]] = icmp ne i8 [[P]], 0
+; CHECK-NEXT: [[TMP0:%.*]] = trunc i8 [[P]] to i1
; CHECK-NEXT: [[C4:%.*]] = call i1 @get_bool()
; CHECK-NEXT: [[B]] = zext i1 [[C4]] to i8
-; CHECK-NEXT: br i1 [[C1]], label [[LOOP]], label [[EXIT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
@@ -1464,7 +1464,7 @@ define i1 @test_icmp_eq_on_valid_bool_range(i8 %x) {
; CHECK-NEXT: [[TMP2:%.*]] = tail call i1 @get_bool()
; CHECK-NEXT: br label [[BB3:%.*]]
; CHECK: bb1:
-; CHECK-NEXT: [[TMP3:%.*]] = icmp eq i8 [[X]], 1
+; CHECK-NEXT: [[TMP3:%.*]] = trunc i8 [[X]] to i1
; CHECK-NEXT: br label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[TMP4:%.*]] = phi i1 [ [[TMP3]], [[BB1]] ], [ [[TMP2]], [[BB2]] ]
@@ -1494,7 +1494,7 @@ define i1 @test_icmp_ne_on_valid_bool_range(i8 %x) {
; CHECK-NEXT: [[TMP2:%.*]] = tail call i1 @get_bool()
; CHECK-NEXT: br label [[BB3:%.*]]
; CHECK: bb1:
-; CHECK-NEXT: [[TMP3:%.*]] = icmp ne i8 [[X]], 0
+; CHECK-NEXT: [[TMP3:%.*]] = trunc i8 [[X]] to i1
; CHECK-NEXT: br label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[TMP4:%.*]] = phi i1 [ [[TMP3]], [[BB1]] ], [ [[TMP2]], [[BB2]] ]
diff --git a/llvm/test/Transforms/JumpThreading/pr33917.ll b/llvm/test/Transforms/JumpThreading/pr33917.ll
index 7d21a4e1781519..20380c769bf173 100644
--- a/llvm/test/Transforms/JumpThreading/pr33917.ll
+++ b/llvm/test/Transforms/JumpThreading/pr33917.ll
@@ -15,16 +15,16 @@ define void @patatino() personality ptr @rust_eh_personality {
; CHECK-LABEL: @patatino(
; CHECK-NEXT: bb9:
; CHECK-NEXT: [[T9:%.*]] = invoke ptr @foo()
-; CHECK-NEXT: to label [[GOOD:%.*]] unwind label [[BAD:%.*]]
+; CHECK-NEXT: to label [[GOOD:%.*]] unwind label [[BAD:%.*]]
; CHECK: bad:
; CHECK-NEXT: [[T10:%.*]] = landingpad { ptr, i32 }
-; CHECK-NEXT: cleanup
+; CHECK-NEXT: cleanup
; CHECK-NEXT: resume { ptr, i32 } [[T10]]
; CHECK: good:
; CHECK-NEXT: [[T11:%.*]] = icmp ne ptr [[T9]], null
; CHECK-NEXT: [[T12:%.*]] = zext i1 [[T11]] to i64
-; CHECK-NEXT: [[COND:%.*]] = icmp eq i64 [[T12]], 1
-; CHECK-NEXT: br i1 [[COND]], label [[IF_TRUE:%.*]], label [[DONE:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = trunc i64 [[T12]] to i1
+; CHECK-NEXT: br i1 [[TMP0]], label [[IF_TRUE:%.*]], label [[DONE:%.*]]
; CHECK: if_true:
; CHECK-NEXT: call void @llvm.assume(i1 [[T11]])
; CHECK-NEXT: br label [[DONE]]
>From bf8d241f6a066d2a8b28ae5a3cf8fa6ea0f19b5f Mon Sep 17 00:00:00 2001
From: YanWQ-monad <YanWQmonad at gmail.com>
Date: Mon, 4 Mar 2024 19:44:54 +0800
Subject: [PATCH 3/3] Fix format
---
llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 73be5f0b016603..a3c078d82ee3dc 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -374,7 +374,7 @@ static bool processCmp(CmpInst *Cmp, LazyValueInfo *LVI) {
return true;
if (processEqualityICmp(Cmp, LVI))
- return true;
+ return true;
return false;
}
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