[llvm-branch-commits] [llvm] PR for llvm/llvm-project#79861 (PR #80832)
via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Tue Feb 6 05:38:30 PST 2024
https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/80832
resolves llvm/llvm-project#79861
>From 2fa03f1b20281a5a7f79b912dc5b2ab5aa1d3c76 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Thu, 1 Feb 2024 12:57:59 +0100
Subject: [PATCH 1/3] [IndVars] Add tests for #79861 (NFC)
(cherry picked from commit c105848fd29d3b46eeb794bb6b10dad04f903b09)
---
.../test/Transforms/IndVarSimplify/pr79861.ll | 104 ++++++++++++++++++
1 file changed, 104 insertions(+)
create mode 100644 llvm/test/Transforms/IndVarSimplify/pr79861.ll
diff --git a/llvm/test/Transforms/IndVarSimplify/pr79861.ll b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
new file mode 100644
index 0000000000000..a8e2aa42a365c
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
@@ -0,0 +1,104 @@
+; 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: call void @use(i64 [[OR]])
+; 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 nuw nsw 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 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]], [[OR]]
+; 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
+}
>From 181baacaf52e766a8247b8af83d60c2a16b14752 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Fri, 2 Feb 2024 10:52:05 +0100
Subject: [PATCH 2/3] [SCEVExpander] Do not reuse disjoint or (#80281)
SCEV treats "or disjoint" the same as "add nsw nuw". However, when
expanding, we cannot generally replace an add SCEV node with an "or
disjoint" instruction. Just dropping the poison flag is insufficient in
this case, we would have to actually convert the or into an add.
This is a partial fix for #79861.
(cherry picked from commit 5b8e1a6ebf11b6e93bcc96a0d009febe4bb3d7bc)
---
llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp | 7 +++++++
llvm/test/Transforms/IndVarSimplify/pr79861.ll | 5 +++--
2 files changed, 10 insertions(+), 2 deletions(-)
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/test/Transforms/IndVarSimplify/pr79861.ll b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
index a8e2aa42a365c..7e267d04c94cc 100644
--- a/llvm/test/Transforms/IndVarSimplify/pr79861.ll
+++ b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
@@ -75,14 +75,15 @@ 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 i64 [[N]], 1
+; 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]], [[OR]]
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i64 [[IV_INC]], [[TMP0]]
; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: ret void
>From 788b31e0f4b995185b79abd248cc0440fb5e8abf Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Mon, 5 Feb 2024 10:11:39 +0100
Subject: [PATCH 3/3] [IndVarSimplify] Fix poison-safety when reusing
instructions (#80458)
IndVars may replace an instruction with one of its operands, if they
have the same SCEV expression. However, such a replacement may be more
poisonous.
First, check whether the operand being poison implies that the
instruction is also poison, in which case the replacement is always
safe. If this fails, check whether SCEV can determine that reusing the
instruction is safe, using the same check as SCEVExpander.
Fixes https://github.com/llvm/llvm-project/issues/79861.
(cherry picked from commit 7d2b6f0b355bc98bbe3aa5bae83316a708da33ee)
---
llvm/lib/Transforms/Utils/SimplifyIndVar.cpp | 18 ++++++++++++++++--
llvm/test/Transforms/IndVarSimplify/pr55925.ll | 4 ++--
llvm/test/Transforms/IndVarSimplify/pr79861.ll | 6 ++++--
3 files changed, 22 insertions(+), 6 deletions(-)
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
index 7e267d04c94cc..6625094496139 100644
--- a/llvm/test/Transforms/IndVarSimplify/pr79861.ll
+++ b/llvm/test/Transforms/IndVarSimplify/pr79861.ll
@@ -12,7 +12,9 @@ define void @or_disjoint() {
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 2, [[ENTRY:%.*]] ], [ [[IV_DEC:%.*]], [[LOOP]] ]
; CHECK-NEXT: [[OR:%.*]] = or disjoint i64 [[IV]], 1
-; CHECK-NEXT: call void @use(i64 [[OR]])
+; 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]]
@@ -44,7 +46,7 @@ define void @add_nowrap_flags(i64 %n) {
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[LOOP]] ]
-; CHECK-NEXT: [[ADD1:%.*]] = add nuw nsw i64 [[IV]], 123
+; 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]]
More information about the llvm-branch-commits
mailing list