[llvm] LICM: extend hoist BO assoc to mul case (PR #106991)
Ramkumar Ramachandra via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 3 03:42:13 PDT 2024
https://github.com/artagnon updated https://github.com/llvm/llvm-project/pull/106991
>From b841070363341fa088334d5ebc2fdd23e5f2c15c Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Mon, 2 Sep 2024 12:50:21 +0100
Subject: [PATCH 1/4] LICM: use PatternMatch, IRBuilder in hoist BO assoc
Use PatternMatch when matching binary operators in hoistBOAssociation,
in order to make it easy to extend (this change is an NFC). Also use
IRBuilder when creating the new invariant instruction, so that the
constant-folder has an opportunity to constant-fold the new Instruction
that we desire to create (this change is not an NFC, and is a minor
improvement).
---
llvm/lib/Transforms/Scalar/LICM.cpp | 39 +++++++++++-----------
llvm/test/Transforms/LICM/sink-foldable.ll | 3 +-
2 files changed, 21 insertions(+), 21 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 86c7dceffc5245..6522b6eab1761b 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2816,40 +2816,41 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
ICFLoopSafetyInfo &SafetyInfo,
MemorySSAUpdater &MSSAU, AssumptionCache *AC,
DominatorTree *DT) {
- auto *BO = dyn_cast<BinaryOperator>(&I);
- if (!BO || !BO->isAssociative())
- return false;
+ using namespace PatternMatch;
- // Only fold ADDs for now.
+ // Transform "(LV op C1) op C2" ==> "LV op (C1 op C2)"
+ Value *LV, *C1, *C2;
+ if (!match(&I, m_BinOp(m_BinOp(m_Value(LV), m_Value(C1)), m_Value(C2))) ||
+ L.isLoopInvariant(LV) || !L.isLoopInvariant(C1) || !L.isLoopInvariant(C2))
+ return false;
+ auto *BO = cast<BinaryOperator>(&I),
+ *BO0 = cast<BinaryOperator>(BO->getOperand(0));
Instruction::BinaryOps Opcode = BO->getOpcode();
- if (Opcode != Instruction::Add)
+ if (BO0->getOpcode() != Opcode || !BO->isAssociative())
return false;
- auto *BO0 = dyn_cast<BinaryOperator>(BO->getOperand(0));
- if (!BO0 || BO0->getOpcode() != Opcode || !BO0->isAssociative() ||
- BO0->hasNUsesOrMore(3))
+ // TODO: Only hoist ADDs for now.
+ if (Opcode != Instruction::Add)
return false;
- // Transform: "(LV op C1) op C2" ==> "LV op (C1 op C2)"
- Value *LV = BO0->getOperand(0);
- Value *C1 = BO0->getOperand(1);
- Value *C2 = BO->getOperand(1);
-
- if (L.isLoopInvariant(LV) || !L.isLoopInvariant(C1) || !L.isLoopInvariant(C2))
+ // This is a heuristic to ensure that code-size doesn't blow up.
+ if (BO0->hasNUsesOrMore(3))
return false;
auto *Preheader = L.getLoopPreheader();
assert(Preheader && "Loop is not in simplify form?");
- auto *Inv = BinaryOperator::Create(Opcode, C1, C2, "invariant.op",
- Preheader->getTerminator()->getIterator());
+ IRBuilder<> Builder(Preheader->getTerminator());
+ auto *Inv = Builder.CreateBinOp(Opcode, C1, C2, "invariant.op");
+
auto *NewBO = BinaryOperator::Create(
Opcode, LV, Inv, BO->getName() + ".reass", BO->getIterator());
// Copy NUW for ADDs if both instructions have it.
- if (Opcode == Instruction::Add && BO->hasNoUnsignedWrap() &&
- BO0->hasNoUnsignedWrap()) {
- Inv->setHasNoUnsignedWrap(true);
+ if (BO->hasNoUnsignedWrap() && BO0->hasNoUnsignedWrap()) {
+ // If the constant-folder didn't kick in, and a new Instruction was created.
+ if (auto *I = dyn_cast<Instruction>(Inv))
+ I->setHasNoUnsignedWrap(true);
NewBO->setHasNoUnsignedWrap(true);
}
diff --git a/llvm/test/Transforms/LICM/sink-foldable.ll b/llvm/test/Transforms/LICM/sink-foldable.ll
index 36e2eab6313dcd..d1cf3de5301b29 100644
--- a/llvm/test/Transforms/LICM/sink-foldable.ll
+++ b/llvm/test/Transforms/LICM/sink-foldable.ll
@@ -77,7 +77,6 @@ return:
define ptr @test2(i32 %j, ptr readonly %P, ptr readnone %Q) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[INVARIANT_OP:%.*]] = add i32 1, 1
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[I_ADDR_0:%.*]] = phi i32 [ [[ADD_REASS:%.*]], [[IF_END:%.*]] ]
@@ -98,7 +97,7 @@ define ptr @test2(i32 %j, ptr readonly %P, ptr readnone %Q) {
; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds ptr, ptr [[ADD_PTR]], i64 [[IDX2_EXT]]
; CHECK-NEXT: [[L1:%.*]] = load ptr, ptr [[ARRAYIDX2]], align 8
; CHECK-NEXT: [[CMP2:%.*]] = icmp ugt ptr [[L1]], [[Q]]
-; CHECK-NEXT: [[ADD_REASS]] = add i32 [[I_ADDR]], [[INVARIANT_OP]]
+; CHECK-NEXT: [[ADD_REASS]] = add i32 [[I_ADDR]], 2
; CHECK-NEXT: br i1 [[CMP2]], label [[LOOPEXIT2:%.*]], label [[FOR_COND]]
; CHECK: loopexit0:
; CHECK-NEXT: [[P0:%.*]] = phi ptr [ null, [[FOR_COND]] ]
>From 90566e779ea8768dea95860b88aad2d128fc2381 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Mon, 2 Sep 2024 13:53:19 +0100
Subject: [PATCH 2/4] LICM: address review
---
llvm/lib/Transforms/Scalar/LICM.cpp | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 6522b6eab1761b..a04de67392ce78 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2826,7 +2826,8 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
auto *BO = cast<BinaryOperator>(&I),
*BO0 = cast<BinaryOperator>(BO->getOperand(0));
Instruction::BinaryOps Opcode = BO->getOpcode();
- if (BO0->getOpcode() != Opcode || !BO->isAssociative())
+ if (BO0->getOpcode() != Opcode || !BO->isAssociative() ||
+ !BO0->isAssociative())
return false;
// TODO: Only hoist ADDs for now.
@@ -2847,7 +2848,8 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
Opcode, LV, Inv, BO->getName() + ".reass", BO->getIterator());
// Copy NUW for ADDs if both instructions have it.
- if (BO->hasNoUnsignedWrap() && BO0->hasNoUnsignedWrap()) {
+ if (Opcode == Instruction::Add && BO->hasNoUnsignedWrap() &&
+ BO0->hasNoUnsignedWrap()) {
// If the constant-folder didn't kick in, and a new Instruction was created.
if (auto *I = dyn_cast<Instruction>(Inv))
I->setHasNoUnsignedWrap(true);
>From 840e6e79751217744116afc1da48ea6122c3e6da Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Tue, 3 Sep 2024 11:36:08 +0100
Subject: [PATCH 3/4] LICM: revert PatternMatch change
---
llvm/lib/Transforms/Scalar/LICM.cpp | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index a04de67392ce78..29d1ffbbb58fc5 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2816,15 +2816,19 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
ICFLoopSafetyInfo &SafetyInfo,
MemorySSAUpdater &MSSAU, AssumptionCache *AC,
DominatorTree *DT) {
- using namespace PatternMatch;
+ auto *BO = dyn_cast<BinaryOperator>(&I);
+ if (!BO)
+ return false;
+ auto *BO0 = dyn_cast<BinaryOperator>(BO->getOperand(0));
+ if (!BO0)
+ return false;
+ Value *LV = BO0->getOperand(0), *C1 = BO0->getOperand(1),
+ *C2 = BO->getOperand(1);
// Transform "(LV op C1) op C2" ==> "LV op (C1 op C2)"
- Value *LV, *C1, *C2;
- if (!match(&I, m_BinOp(m_BinOp(m_Value(LV), m_Value(C1)), m_Value(C2))) ||
- L.isLoopInvariant(LV) || !L.isLoopInvariant(C1) || !L.isLoopInvariant(C2))
+ if (L.isLoopInvariant(LV) || !L.isLoopInvariant(C1) || !L.isLoopInvariant(C2))
return false;
- auto *BO = cast<BinaryOperator>(&I),
- *BO0 = cast<BinaryOperator>(BO->getOperand(0));
+
Instruction::BinaryOps Opcode = BO->getOpcode();
if (BO0->getOpcode() != Opcode || !BO->isAssociative() ||
!BO0->isAssociative())
>From 662772b4121738c6b7712842daeb744be4c2acde Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Mon, 2 Sep 2024 14:29:09 +0100
Subject: [PATCH 4/4] LICM: extend hoist BO assoc to mul case
Trivially extend hoistBOAssociation to also handle the BinaryOperator
Mul.
Alive2 proofs: https://alive2.llvm.org/ce/z/zjtR5g
---
llvm/lib/Transforms/Scalar/LICM.cpp | 4 +-
llvm/test/Transforms/LICM/hoist-binop.ll | 136 ++++++++++++++++--
.../LICM/update-scev-after-hoist.ll | 34 ++++-
3 files changed, 155 insertions(+), 19 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 29d1ffbbb58fc5..900dc5cb1863d3 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2834,8 +2834,8 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
!BO0->isAssociative())
return false;
- // TODO: Only hoist ADDs for now.
- if (Opcode != Instruction::Add)
+ // TODO: Only hoist ADDs and MULs for now.
+ if (Opcode != Instruction::Add && Opcode != Instruction::Mul)
return false;
// This is a heuristic to ensure that code-size doesn't blow up.
diff --git a/llvm/test/Transforms/LICM/hoist-binop.ll b/llvm/test/Transforms/LICM/hoist-binop.ll
index 7a309ea294fc85..991cab02b5d959 100644
--- a/llvm/test/Transforms/LICM/hoist-binop.ll
+++ b/llvm/test/Transforms/LICM/hoist-binop.ll
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes=licm < %s | FileCheck %s
-; Fold ADD and remove old op if unused.
+; Hoist ADD and remove old op if unused.
define void @add_one_use(i64 %c1, i64 %c2) {
; CHECK-LABEL: @add_one_use(
; CHECK-NEXT: entry:
@@ -22,8 +22,28 @@ loop:
br label %loop
}
-; Fold ADD and copy NUW if both ops have it.
-; https://alive2.llvm.org/ce/z/bPAT7Z
+; Hoist MUL and remove old op if unused.
+define void @mul_one_use(i64 %c1, i64 %c2) {
+; CHECK-LABEL: @mul_one_use(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[FACTOR_OP_MUL:%.*]] = mul i64 [[C1:%.*]], [[C2:%.*]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[STEP_ADD_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD_REASS]] = mul i64 [[INDEX]], [[FACTOR_OP_MUL]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = mul i64 %index, %c1
+ %index.next = mul i64 %step.add, %c2
+ br label %loop
+}
+
+; Hoist ADD and copy NUW if both ops have it.
define void @add_nuw(i64 %c1, i64 %c2) {
; CHECK-LABEL: @add_nuw(
; CHECK-NEXT: entry:
@@ -47,7 +67,31 @@ loop:
br label %loop
}
-; Fold ADD but don't copy NUW if only one op has it.
+; Hoist MUL and drop NUW if both ops have it.
+define void @mul_nuw(i64 %c1, i64 %c2) {
+; CHECK-LABEL: @mul_nuw(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = mul i64 [[C1:%.*]], [[C2:%.*]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = mul nuw i64 [[INDEX]], [[C1]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = mul i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = mul nuw i64 %index, %c1
+ call void @use(i64 %step.add)
+ %index.next = mul nuw i64 %step.add, %c2
+ br label %loop
+}
+
+; Hoist ADD but don't copy NUW if only one op has it.
define void @add_no_nuw(i64 %c1, i64 %c2) {
; CHECK-LABEL: @add_no_nuw(
; CHECK-NEXT: entry:
@@ -71,7 +115,31 @@ loop:
br label %loop
}
-; Fold ADD but don't copy NSW if one op has it.
+; Hoist MUL and drop NUW if only one op has it.
+define void @mul_no_nuw(i64 %c1, i64 %c2) {
+; CHECK-LABEL: @mul_no_nuw(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = mul i64 [[C1:%.*]], [[C2:%.*]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = mul i64 [[INDEX]], [[C1]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = mul i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = mul i64 %index, %c1
+ call void @use(i64 %step.add)
+ %index.next = mul nuw i64 %step.add, %c2
+ br label %loop
+}
+
+; Hoist ADD but don't copy NSW if one op has it.
define void @add_no_nsw(i64 %c1, i64 %c2) {
; CHECK-LABEL: @add_no_nsw(
; CHECK-NEXT: entry:
@@ -95,7 +163,31 @@ loop:
br label %loop
}
-; Fold ADD but don't copy NSW even if both ops have it.
+; Hoist MUL and drop NSW if one op has it.
+define void @mul_no_nsw(i64 %c1, i64 %c2) {
+; CHECK-LABEL: @mul_no_nsw(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = mul i64 [[C1:%.*]], [[C2:%.*]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = mul i64 [[INDEX]], [[C1]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = mul i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = mul i64 %index, %c1
+ call void @use(i64 %step.add)
+ %index.next = mul nsw i64 %step.add, %c2
+ br label %loop
+}
+
+; Hoist ADD but don't copy NSW even if both ops have it.
define void @add_no_nsw_2(i64 %c1, i64 %c2) {
; CHECK-LABEL: @add_no_nsw_2(
; CHECK-NEXT: entry:
@@ -119,7 +211,31 @@ loop:
br label %loop
}
-; Don't fold if the ops are different (even if they are both associative).
+; Hoist MUL and drop NSW if both ops have it.
+define void @mul_no_nsw_2(i64 %c1, i64 %c2) {
+; CHECK-LABEL: @mul_no_nsw_2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = mul i64 [[C1:%.*]], [[C2:%.*]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = mul nsw i64 [[INDEX]], [[C1]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = mul i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = mul nsw i64 %index, %c1
+ call void @use(i64 %step.add)
+ %index.next = mul nsw i64 %step.add, %c2
+ br label %loop
+}
+
+; Don't hoist if the ops are different (even if they are both associative).
define void @diff_ops(i64 %c1, i64 %c2) {
; CHECK-LABEL: @diff_ops(
; CHECK-NEXT: entry:
@@ -142,7 +258,7 @@ loop:
br label %loop
}
-; Don't fold if the ops are not associative.
+; Don't hoist if the ops are not associative.
define void @noassoc_ops(i64 %c1, i64 %c2) {
; CHECK-LABEL: @noassoc_ops(
; CHECK-NEXT: entry:
@@ -165,7 +281,7 @@ loop:
br label %loop
}
-; Don't fold floating-point ops, even if they are associative. This would be
+; Don't hoist floating-point ops, even if they are associative. This would be
; valid, but is currently disabled.
define void @fadd(float %c1, float %c2) {
; CHECK-LABEL: @fadd(
@@ -189,7 +305,7 @@ loop:
br label %loop
}
-; Don't fold if the intermediate op has more than two uses. This is an
+; Don't hoist if the intermediate op has more than two uses. This is an
; heuristic that can be adjusted if warranted. Currently we are being
; conservative to minimise potential impact in code size.
define void @not_many_uses(i64 %c1, i64 %c2, i64 %c3) {
diff --git a/llvm/test/Transforms/LICM/update-scev-after-hoist.ll b/llvm/test/Transforms/LICM/update-scev-after-hoist.ll
index fc45b8fce1766a..e303d04ce31913 100644
--- a/llvm/test/Transforms/LICM/update-scev-after-hoist.ll
+++ b/llvm/test/Transforms/LICM/update-scev-after-hoist.ll
@@ -1,13 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
; RUN: opt -S -passes='loop-unroll,loop-mssa(licm),print<scalar-evolution>' -unroll-count=4 -disable-output < %s 2>&1 | FileCheck %s --check-prefix=SCEV-EXPR
define i16 @main() {
-; SCEV-EXPR: Classifying expressions for: @main
-; SCEV-EXPR-NEXT: %mul = phi i16 [ 1, %entry ], [ %mul.n.3, %loop ]
-; SCEV-EXPR-NEXT: --> %mul U: [0,-15) S: [-32768,32753) Exits: 4096 LoopDispositions: { %loop: Variant }
-; SCEV-EXPR-NEXT: %div = phi i16 [ 32767, %entry ], [ %div.n.3, %loop ]
-; SCEV-EXPR-NEXT: --> %div U: [-2048,-32768) S: [-2048,-32768) Exits: 7 LoopDispositions: { %loop: Variant }
-; SCEV-EXPR-NEXT: %mul.n.reass.reass = mul i16 %mul, 8
-; SCEV-EXPR-NEXT: --> (8 * %mul) U: [0,-7) S: [-32768,32761) Exits: -32768 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-LABEL: 'main'
+; SCEV-EXPR-NEXT: Classifying expressions for: @main
+; SCEV-EXPR-NEXT: %mul = phi i16 [ 1, %entry ], [ %mul.n.3.reass, %loop ]
+; SCEV-EXPR-NEXT: --> %mul U: [0,-15) S: [-32768,32753) Exits: 4096 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %div = phi i16 [ 32767, %entry ], [ %div.n.3, %loop ]
+; SCEV-EXPR-NEXT: --> %div U: [-2048,-32768) S: [-2048,-32768) Exits: 7 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %mul.n.reass.reass = mul i16 %mul, 8
+; SCEV-EXPR-NEXT: --> (8 * %mul) U: [0,-7) S: [-32768,32761) Exits: -32768 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %div.n = sdiv i16 %div, 2
+; SCEV-EXPR-NEXT: --> %div.n U: [-16384,16384) S: [-16384,16384) Exits: 3 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %div.n.1 = sdiv i16 %div.n, 2
+; SCEV-EXPR-NEXT: --> %div.n.1 U: [-8192,8192) S: [-8192,8192) Exits: 1 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %div.n.2 = sdiv i16 %div.n.1, 2
+; SCEV-EXPR-NEXT: --> %div.n.2 U: [-4096,4096) S: [-4096,4096) Exits: 0 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %mul.n.3.reass = mul i16 %mul, 16
+; SCEV-EXPR-NEXT: --> (16 * %mul) U: [0,-15) S: [-32768,32753) Exits: 0 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %div.n.3 = sdiv i16 %div.n.2, 2
+; SCEV-EXPR-NEXT: --> %div.n.3 U: [-2048,2048) S: [-2048,2048) Exits: 0 LoopDispositions: { %loop: Variant }
+; SCEV-EXPR-NEXT: %mul.lcssa = phi i16 [ %mul.n.reass.reass, %loop ]
+; SCEV-EXPR-NEXT: --> (8 * %mul) U: [0,-7) S: [-32768,32761) --> -32768 U: [-32768,-32767) S: [-32768,-32767)
+; SCEV-EXPR-NEXT: Determining loop execution counts for: @main
+; SCEV-EXPR-NEXT: Loop %loop: backedge-taken count is i32 3
+; SCEV-EXPR-NEXT: Loop %loop: constant max backedge-taken count is i32 3
+; SCEV-EXPR-NEXT: Loop %loop: symbolic max backedge-taken count is i32 3
+; SCEV-EXPR-NEXT: Loop %loop: Trip multiple is 4
+;
entry:
br label %loop
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