[llvm] [InstCombine] Fix saturated add canonicalization (PR #97973)
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Tue Jul 9 17:05:05 PDT 2024
https://github.com/AtariDreams updated https://github.com/llvm/llvm-project/pull/97973
>From 9553aa13158e0f7c734319930241f6c1245e97df Mon Sep 17 00:00:00 2001
From: Rose <gfunni234 at gmail.com>
Date: Sun, 7 Jul 2024 17:51:02 -0400
Subject: [PATCH 1/3] [InstCombine] Fix saturated add canonicalization
For some reason, LLVM is not considering X u > C, a, b to be the same as X <= C, b, a.
Move that to after the canonicalization.
Alive2 Proof:
https://alive2.llvm.org/ce/z/8QbZfx
---
.../InstCombine/InstCombineSelect.cpp | 33 +++++++++++++++----
.../InstCombine/saturating-add-sub.ll | 20 +++++++----
2 files changed, 40 insertions(+), 13 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 394dfca262e13..abfe3153ba0be 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -978,13 +978,6 @@ static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
ICmpInst::Predicate Pred = Cmp->getPredicate();
Value *X;
const APInt *C, *CmpC;
- if (Pred == ICmpInst::ICMP_ULT &&
- match(TVal, m_Add(m_Value(X), m_APInt(C))) && X == Cmp0 &&
- match(FVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
- // (X u< ~C) ? (X + C) : -1 --> uadd.sat(X, C)
- return Builder.CreateBinaryIntrinsic(
- Intrinsic::uadd_sat, X, ConstantInt::get(X->getType(), *C));
- }
// Match unsigned saturated add of 2 variables with an unnecessary 'not'.
// There are 8 commuted variants.
@@ -996,6 +989,32 @@ static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
if (!match(TVal, m_AllOnes()))
return nullptr;
+ if ((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) &&
+ match(FVal, m_Add(m_Specific(Cmp0), m_APInt(C))) &&
+ match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
+ // (X u> ~C) ? -1 : (X + C) --> uadd.sat(X, C)
+ return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, Cmp0,
+ ConstantInt::get(Cmp0->getType(), *C));
+ }
+
+ if (Pred == ICmpInst::ICMP_UGE &&
+ match(FVal, m_Add(m_Specific(Cmp0), m_APInt(C))) &&
+ match(TVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) &&
+ *CmpC == (~*C + 1)) {
+ // (X u> ~C + 1) ? -1 : (X + C) --> uadd.sat(X, C)
+ return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, Cmp0,
+ ConstantInt::get(Cmp0->getType(), *C));
+ }
+
+ if (Pred == ICmpInst::ICMP_UGT &&
+ match(FVal, m_Add(m_Specific(Cmp0), m_APInt(C))) &&
+ match(TVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) &&
+ *CmpC == (~*C - 1)) {
+ // (X u> ~C - 1) ? -1 : (X + C) --> uadd.sat(X, C)
+ return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, Cmp0,
+ ConstantInt::get(Cmp0->getType(), *C));
+ }
+
// Canonicalize predicate to less-than or less-or-equal-than.
if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) {
std::swap(Cmp0, Cmp1);
diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
index bf1568f1cd8c0..19736c0baac77 100644
--- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -1395,6 +1395,18 @@ define i32 @uadd_sat(i32 %x, i32 %y) {
%r = select i1 %c, i32 -1, i32 %a
ret i32 %r
}
+
+define i32 @uadd_sat_flipped(i32 %x) {
+; CHECK-LABEL: @uadd_sat_flipped(
+; CHECK-NEXT: [[COND:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 9)
+; CHECK-NEXT: ret i32 [[COND]]
+;
+ %cmp = icmp uge i32 %x, -10
+ %add = add i32 %x, 9
+ %cond = select i1 %cmp, i32 -1, i32 %add
+ ret i32 %cond
+}
+
define i32 @uadd_sat_nonstrict(i32 %x, i32 %y) {
; CHECK-LABEL: @uadd_sat_nonstrict(
; CHECK-NEXT: [[R:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 [[Y:%.*]])
@@ -1736,9 +1748,7 @@ define i32 @uadd_sat_not_commute_select_uge_commute_add(i32 %x, i32 %y) {
define i32 @uadd_sat_constant(i32 %x) {
; CHECK-LABEL: @uadd_sat_constant(
-; CHECK-NEXT: [[A:%.*]] = add i32 [[X:%.*]], 42
-; CHECK-NEXT: [[C:%.*]] = icmp ugt i32 [[X]], -43
-; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 -1, i32 [[A]]
+; CHECK-NEXT: [[R:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 42)
; CHECK-NEXT: ret i32 [[R]]
;
%a = add i32 %x, 42
@@ -1804,9 +1814,7 @@ define i32 @uadd_sat_canon_y_nuw(i32 %x, i32 %y) {
define <4 x i32> @uadd_sat_constant_vec(<4 x i32> %x) {
; CHECK-LABEL: @uadd_sat_constant_vec(
-; CHECK-NEXT: [[A:%.*]] = add <4 x i32> [[X:%.*]], <i32 42, i32 42, i32 42, i32 42>
-; CHECK-NEXT: [[C:%.*]] = icmp ugt <4 x i32> [[X]], <i32 -43, i32 -43, i32 -43, i32 -43>
-; CHECK-NEXT: [[R:%.*]] = select <4 x i1> [[C]], <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>, <4 x i32> [[A]]
+; CHECK-NEXT: [[R:%.*]] = call <4 x i32> @llvm.uadd.sat.v4i32(<4 x i32> [[X:%.*]], <4 x i32> <i32 42, i32 42, i32 42, i32 42>)
; CHECK-NEXT: ret <4 x i32> [[R]]
;
%a = add <4 x i32> %x, <i32 42, i32 42, i32 42, i32 42>
>From e7c598f2a810ed2b90ed5472c3ff928c45368568 Mon Sep 17 00:00:00 2001
From: AtariDreams <gfunni234 at gmail.com>
Date: Tue, 9 Jul 2024 19:58:48 -0400
Subject: [PATCH 2/3] Add more test cases
---
.../InstCombine/saturating-add-sub.ll | 33 +++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
index 19736c0baac77..78b784676e355 100644
--- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -1407,6 +1407,39 @@ define i32 @uadd_sat_flipped(i32 %x) {
ret i32 %cond
}
+define i32 @uadd_sat_flipped2(i32 %x) {
+; CHECK-LABEL: @uadd_sat_flipped2(
+; CHECK-NEXT: [[COND:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 9)
+; CHECK-NEXT: ret i32 [[COND]]
+;
+ %cmp = icmp ugt i32 %x, -10
+ %add = add i32 %x, 9
+ %cond = select i1 %cmp, i32 -1, i32 %add
+ ret i32 %cond
+}
+
+define i32 @uadd_sat_flipped3(i32 %x) {
+; CHECK-LABEL: @uadd_sat_flipped3(
+; CHECK-NEXT: [[COND:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 9)
+; CHECK-NEXT: ret i32 [[COND]]
+;
+ %cmp = icmp ugt i32 %x, -11
+ %add = add i32 %x, 9
+ %cond = select i1 %cmp, i32 -1, i32 %add
+ ret i32 %cond
+}
+
+define i32 @uadd_sat_flipped4(i32 %x) {
+; CHECK-LABEL: @uadd_sat_flipped4(
+; CHECK-NEXT: [[COND:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 9)
+; CHECK-NEXT: ret i32 [[COND]]
+;
+ %cmp = icmp uge i32 %x, -9
+ %add = add i32 %x, 9
+ %cond = select i1 %cmp, i32 -1, i32 %add
+ ret i32 %cond
+}
+
define i32 @uadd_sat_nonstrict(i32 %x, i32 %y) {
; CHECK-LABEL: @uadd_sat_nonstrict(
; CHECK-NEXT: [[R:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 [[Y:%.*]])
>From fabfc05eb2e1202281acffcc17156f43fb63065d Mon Sep 17 00:00:00 2001
From: AtariDreams <gfunni234 at gmail.com>
Date: Tue, 9 Jul 2024 20:04:57 -0400
Subject: [PATCH 3/3] Make suggested edits
---
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index abfe3153ba0be..1c10b7b2fa07d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -999,17 +999,15 @@ static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
if (Pred == ICmpInst::ICMP_UGE &&
match(FVal, m_Add(m_Specific(Cmp0), m_APInt(C))) &&
- match(TVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) &&
- *CmpC == (~*C + 1)) {
- // (X u> ~C + 1) ? -1 : (X + C) --> uadd.sat(X, C)
+ match(TVal, m_AllOnes()) && match(Cmp1, m_SpecificInt(-*C)) {
+ // (X u> -C) ? -1 : (X + C) --> uadd.sat(X, C)
return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, Cmp0,
ConstantInt::get(Cmp0->getType(), *C));
}
if (Pred == ICmpInst::ICMP_UGT &&
match(FVal, m_Add(m_Specific(Cmp0), m_APInt(C))) &&
- match(TVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) &&
- *CmpC == (~*C - 1)) {
+ match(TVal, m_AllOnes()) && match(Cmp1, m_SpecificInt(~*C - 1)) {
// (X u> ~C - 1) ? -1 : (X + C) --> uadd.sat(X, C)
return Builder.CreateBinaryIntrinsic(Intrinsic::uadd_sat, Cmp0,
ConstantInt::get(Cmp0->getType(), *C));
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