[llvm-branch-commits] [llvm] PR for llvm/llvm-project#79861 (PR #80832)
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llvm-branch-commits at lists.llvm.org
Tue Feb 6 05:39:03 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: None (llvmbot)
<details>
<summary>Changes</summary>
resolves llvm/llvm-project#<!-- -->79861
---
Full diff: https://github.com/llvm/llvm-project/pull/80832.diff
4 Files Affected:
- (modified) llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp (+7)
- (modified) llvm/lib/Transforms/Utils/SimplifyIndVar.cpp (+16-2)
- (modified) llvm/test/Transforms/IndVarSimplify/pr55925.ll (+2-2)
- (added) llvm/test/Transforms/IndVarSimplify/pr79861.ll (+107)
``````````diff
diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index a1d7f0f9ba0f7..e6f93e72c98a7 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -1401,6 +1401,13 @@ canReuseInstruction(ScalarEvolution &SE, const SCEV *S, Instruction *I,
if (!I)
return false;
+ // Disjoint or instructions are interpreted as adds by SCEV. However, we
+ // can't replace an arbitrary add with disjoint or, even if we drop the
+ // flag. We would need to convert the or into an add.
+ if (auto *PDI = dyn_cast<PossiblyDisjointInst>(I))
+ if (PDI->isDisjoint())
+ return false;
+
// FIXME: Ignore vscale, even though it technically could be poison. Do this
// because SCEV currently assumes it can't be poison. Remove this special
// case once we proper model when vscale can be poison.
diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index 0ed3324a27b6c..1b142f14d8113 100644
--- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -16,6 +16,7 @@
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
@@ -713,8 +714,11 @@ bool SimplifyIndvar::replaceFloatIVWithIntegerIV(Instruction *UseInst) {
bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
Instruction *IVOperand) {
if (!SE->isSCEVable(UseInst->getType()) ||
- (UseInst->getType() != IVOperand->getType()) ||
- (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
+ UseInst->getType() != IVOperand->getType())
+ return false;
+
+ const SCEV *UseSCEV = SE->getSCEV(UseInst);
+ if (UseSCEV != SE->getSCEV(IVOperand))
return false;
// getSCEV(X) == getSCEV(Y) does not guarantee that X and Y are related in the
@@ -742,6 +746,16 @@ bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
if (!LI->replacementPreservesLCSSAForm(UseInst, IVOperand))
return false;
+ // Make sure the operand is not more poisonous than the instruction.
+ if (!impliesPoison(IVOperand, UseInst)) {
+ SmallVector<Instruction *> DropPoisonGeneratingInsts;
+ if (!SE->canReuseInstruction(UseSCEV, IVOperand, DropPoisonGeneratingInsts))
+ return false;
+
+ for (Instruction *I : DropPoisonGeneratingInsts)
+ I->dropPoisonGeneratingFlagsAndMetadata();
+ }
+
LLVM_DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n');
SE->forgetValue(UseInst);
diff --git a/llvm/test/Transforms/IndVarSimplify/pr55925.ll b/llvm/test/Transforms/IndVarSimplify/pr55925.ll
index 420fc209949d4..312a8295ccdc9 100644
--- a/llvm/test/Transforms/IndVarSimplify/pr55925.ll
+++ b/llvm/test/Transforms/IndVarSimplify/pr55925.ll
@@ -18,9 +18,9 @@ define void @test(ptr %p) personality ptr undef {
; CHECK-NEXT: [[RES:%.*]] = invoke i32 @foo(i32 returned [[TMP0]])
; CHECK-NEXT: to label [[LOOP_LATCH]] unwind label [[EXIT:%.*]]
; CHECK: loop.latch:
-; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add i64 [[INDVARS_IV]], 1
; CHECK-NEXT: [[TMP1:%.*]] = trunc i64 [[INDVARS_IV]] to i32
; CHECK-NEXT: [[TMP2:%.*]] = call i32 @foo(i32 [[TMP1]])
+; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add i64 [[INDVARS_IV]], 1
; CHECK-NEXT: br label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: [[LP:%.*]] = landingpad { ptr, i32 }
@@ -64,8 +64,8 @@ define void @test_critedge(i1 %c, ptr %p) personality ptr undef {
; CHECK-NEXT: br label [[LOOP_LATCH]]
; CHECK: loop.latch:
; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ [[TMP1]], [[LOOP_INVOKE]] ], [ 0, [[LOOP_OTHER]] ]
-; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add i64 [[INDVARS_IV]], 1
; CHECK-NEXT: [[TMP2:%.*]] = call i32 @foo(i32 [[PHI]])
+; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add i64 [[INDVARS_IV]], 1
; CHECK-NEXT: br label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: [[LP:%.*]] = landingpad { ptr, i32 }
diff --git a/llvm/test/Transforms/IndVarSimplify/pr79861.ll b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
new file mode 100644
index 0000000000000..6625094496139
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
@@ -0,0 +1,107 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -S -passes=indvars < %s | FileCheck %s
+
+target datalayout = "n64"
+
+declare void @use(i64)
+
+define void @or_disjoint() {
+; CHECK-LABEL: define void @or_disjoint() {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 2, [[ENTRY:%.*]] ], [ [[IV_DEC:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OR:%.*]] = or disjoint i64 [[IV]], 1
+; CHECK-NEXT: [[ADD:%.*]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[SEL:%.*]] = select i1 false, i64 [[OR]], i64 [[ADD]]
+; CHECK-NEXT: call void @use(i64 [[SEL]])
+; CHECK-NEXT: [[IV_DEC]] = add nsw i64 [[IV]], -1
+; CHECK-NEXT: [[EXIT_COND:%.*]] = icmp eq i64 [[IV_DEC]], 0
+; CHECK-NEXT: br i1 [[EXIT_COND]], label [[EXIT:%.*]], label [[LOOP]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 2, %entry ], [ %iv.dec, %loop ]
+ %or = or disjoint i64 %iv, 1
+ %add = add nsw i64 %iv, 1
+ %sel = select i1 false, i64 %or, i64 %add
+ call void @use(i64 %sel)
+
+ %iv.dec = add nsw i64 %iv, -1
+ %exit.cond = icmp eq i64 %iv.dec, 0
+ br i1 %exit.cond, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+define void @add_nowrap_flags(i64 %n) {
+; CHECK-LABEL: define void @add_nowrap_flags(
+; CHECK-SAME: i64 [[N:%.*]]) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[ADD1:%.*]] = add i64 [[IV]], 123
+; CHECK-NEXT: call void @use(i64 [[ADD1]])
+; CHECK-NEXT: [[IV_INC]] = add i64 [[IV]], 1
+; CHECK-NEXT: [[EXIT_COND:%.*]] = icmp eq i64 [[IV_INC]], [[N]]
+; CHECK-NEXT: br i1 [[EXIT_COND]], label [[EXIT:%.*]], label [[LOOP]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.inc, %loop ]
+ %add1 = add nuw nsw i64 %iv, 123
+ %add2 = add i64 %iv, 123
+ %sel = select i1 false, i64 %add1, i64 %add2
+ call void @use(i64 %sel)
+
+ %iv.inc = add i64 %iv, 1
+ %exit.cond = icmp eq i64 %iv.inc, %n
+ br i1 %exit.cond, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+
+define void @expander_or_disjoint(i64 %n) {
+; CHECK-LABEL: define void @expander_or_disjoint(
+; CHECK-SAME: i64 [[N:%.*]]) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[OR:%.*]] = or disjoint i64 [[N]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[N]], 1
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_INC]] = add i64 [[IV]], 1
+; CHECK-NEXT: [[ADD:%.*]] = add i64 [[IV]], [[OR]]
+; CHECK-NEXT: call void @use(i64 [[ADD]])
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i64 [[IV_INC]], [[TMP0]]
+; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ %or = or disjoint i64 %n, 1
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.inc, %loop ]
+ %iv.inc = add i64 %iv, 1
+ %add = add i64 %iv, %or
+ call void @use(i64 %add)
+ %cmp = icmp ult i64 %iv, %n
+ br i1 %cmp, label %loop, label %exit
+
+exit:
+ ret void
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/80832
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