[llvm] [SCEV] Remove ControlsOnlyExit only used for unsimplified IR. (PR #195052)
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 30 03:33:30 PDT 2026
https://github.com/fhahn created https://github.com/llvm/llvm-project/pull/195052
ControlsOnlyExit is only set to true for And/Or with a neutral element, i.e. unsimplified IR. Remove the complexity, relying on IR simplifications instead.
>From 0a7ff9c341e4b624cdec97cef7b65980da036146 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Thu, 30 Apr 2026 11:18:03 +0100
Subject: [PATCH] [SCEV] Remove ControlsOnlyExit only used for unsimplified IR.
ControlsOnlyExit is only set to true for And/Or with a neutral element,
i.e. unsimplified IR. Remove the complexity, relying on IR
simplifications instead.
---
llvm/include/llvm/Analysis/ScalarEvolution.h | 2 +-
llvm/lib/Analysis/ScalarEvolution.cpp | 12 +-----
.../trip-count-andor-selectform.ll | 40 ++++++++-----------
.../ScalarEvolution/trip-count-andor.ll | 40 ++++++++-----------
4 files changed, 35 insertions(+), 59 deletions(-)
diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 5c01da0855f66..8b199e7cb05fd 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -2106,7 +2106,7 @@ class ScalarEvolution {
bool AllowPredicates);
std::optional<ScalarEvolution::ExitLimit> computeExitLimitFromCondFromBinOp(
ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
- bool ControlsOnlyExit, bool AllowPredicates);
+ bool AllowPredicates);
/// Compute the number of times the backedge of the specified loop will
/// execute if its exit condition were a conditional branch of the ICmpInst
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 676292ebe0346..d0af9f9e52e79 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9298,7 +9298,7 @@ ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
bool ControlsOnlyExit, bool AllowPredicates) {
// Handle BinOp conditions (And, Or).
if (auto LimitFromBinOp = computeExitLimitFromCondFromBinOp(
- Cache, L, ExitCond, ExitIfTrue, ControlsOnlyExit, AllowPredicates))
+ Cache, L, ExitCond, ExitIfTrue, AllowPredicates))
return *LimitFromBinOp;
// With an icmp, it may be feasible to compute an exact backedge-taken count.
@@ -9358,7 +9358,7 @@ ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
std::optional<ScalarEvolution::ExitLimit>
ScalarEvolution::computeExitLimitFromCondFromBinOp(
ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
- bool ControlsOnlyExit, bool AllowPredicates) {
+ bool AllowPredicates) {
// Check if the controlling expression for this loop is an And or Or.
Value *Op0, *Op1;
bool IsAnd;
@@ -9369,14 +9369,6 @@ ScalarEvolution::computeExitLimitFromCondFromBinOp(
else
return std::nullopt;
- // Be robust against unsimplified IR for the form "op i1 X, NeutralElement".
- const Constant *NeutralElement = ConstantInt::get(ExitCond->getType(), IsAnd);
- if (Op0 == NeutralElement)
- std::swap(Op0, Op1);
- if (Op1 == NeutralElement)
- return computeExitLimitFromCondCached(Cache, L, Op0, ExitIfTrue,
- ControlsOnlyExit, AllowPredicates);
-
// A sub-condition of a non-trivial binop never solely controls the exit,
// whether we exit always depends on both conditions.
ExitLimit EL0 = computeExitLimitFromCondCached(
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-andor-selectform.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-andor-selectform.ll
index 7e052d65d1c8e..26f00ea5ca36a 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count-andor-selectform.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count-andor-selectform.ll
@@ -7,10 +7,9 @@ target triple = "x86_64-unknown-linux-gnu"
define void @unsimplified_and1(i32 %n) {
; CHECK-LABEL: 'unsimplified_and1'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and1
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -29,10 +28,9 @@ leave:
define void @unsimplified_and2(i32 %n) {
; CHECK-LABEL: 'unsimplified_and2'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and2
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -137,10 +135,9 @@ leave:
define void @unsimplified_or3(i32 %n) {
; CHECK-LABEL: 'unsimplified_or3'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_or3
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -159,10 +156,9 @@ leave:
define void @unsimplified_or4(i32 %n) {
; CHECK-LABEL: 'unsimplified_or4'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_or4
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -181,10 +177,9 @@ leave:
define void @reversed_and1(i32 %n) {
; CHECK-LABEL: 'reversed_and1'
; CHECK-NEXT: Determining loop execution counts for: @reversed_and1
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -203,10 +198,9 @@ leave:
define void @reversed_and2(i32 %n) {
; CHECK-LABEL: 'reversed_and2'
; CHECK-NEXT: Determining loop execution counts for: @reversed_and2
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -311,10 +305,9 @@ leave:
define void @reversed_or3(i32 %n) {
; CHECK-LABEL: 'reversed_or3'
; CHECK-NEXT: Determining loop execution counts for: @reversed_or3
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -333,10 +326,9 @@ leave:
define void @reversed_or4(i32 %n) {
; CHECK-LABEL: 'reversed_or4'
; CHECK-NEXT: Determining loop execution counts for: @reversed_or4
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
index 8df88f2d58621..34bf853b6be02 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
@@ -7,10 +7,9 @@ target triple = "x86_64-unknown-linux-gnu"
define void @unsimplified_and1(i32 %n) {
; CHECK-LABEL: 'unsimplified_and1'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and1
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -29,10 +28,9 @@ leave:
define void @unsimplified_and2(i32 %n) {
; CHECK-LABEL: 'unsimplified_and2'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and2
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -137,10 +135,9 @@ leave:
define void @unsimplified_or3(i32 %n) {
; CHECK-LABEL: 'unsimplified_or3'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_or3
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -159,10 +156,9 @@ leave:
define void @unsimplified_or4(i32 %n) {
; CHECK-LABEL: 'unsimplified_or4'
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_or4
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -181,10 +177,9 @@ leave:
define void @reversed_and1(i32 %n) {
; CHECK-LABEL: 'reversed_and1'
; CHECK-NEXT: Determining loop execution counts for: @reversed_and1
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -203,10 +198,9 @@ leave:
define void @reversed_and2(i32 %n) {
; CHECK-LABEL: 'reversed_and2'
; CHECK-NEXT: Determining loop execution counts for: @reversed_and2
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
;
entry:
br label %loop
@@ -311,10 +305,9 @@ leave:
define void @reversed_or3(i32 %n) {
; CHECK-LABEL: 'reversed_or3'
; CHECK-NEXT: Determining loop execution counts for: @reversed_or3
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -333,10 +326,9 @@ leave:
define void @reversed_or4(i32 %n) {
; CHECK-LABEL: 'reversed_or4'
; CHECK-NEXT: Determining loop execution counts for: @reversed_or4
-; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 -1
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is %n
-; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
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