atmnpatel updated this revision to Diff 297069.
atmnpatel added a comment.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Fixes.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D86844/new/
https://reviews.llvm.org/D86844
Files:
clang/test/Misc/loop-opt-setup.c
llvm/include/llvm/Analysis/LoopInfo.h
llvm/include/llvm/Analysis/LoopInfoImpl.h
llvm/include/llvm/Transforms/Utils/LoopUtils.h
llvm/lib/Transforms/Scalar/LoopDeletion.cpp
llvm/lib/Transforms/Utils/LoopUtils.cpp
llvm/test/Other/loop-deletion-printer.ll
llvm/test/Other/loop-pm-invalidation.ll
llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll
llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
llvm/test/Transforms/LoopDeletion/basic-remark.ll
llvm/test/Transforms/LoopDeletion/diundef.ll
llvm/test/Transforms/LoopDeletion/invalidation.ll
llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll
llvm/test/Transforms/LoopDeletion/multiple-exits.ll
llvm/test/Transforms/LoopDeletion/mustprogress.ll
llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll
llvm/test/Transforms/SCCP/calltest.ll
llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll
Index: llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll
===================================================================
--- llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll
+++ llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll
@@ -7,7 +7,7 @@
target triple = "x86_64-unknown-linux-gnu"
-define void @pr37888() {
+define void @pr37888() willreturn {
; CHECK-LABEL: define void @pr37888()
entry:
%tobool = icmp ne i16 undef, 0
Index: llvm/test/Transforms/SCCP/calltest.ll
===================================================================
--- llvm/test/Transforms/SCCP/calltest.ll
+++ llvm/test/Transforms/SCCP/calltest.ll
@@ -4,7 +4,7 @@
%empty = type {}
declare %empty @has_side_effects()
-define double @test_0(i32 %param) {
+define double @test_0(i32 %param) willreturn {
; CHECK-LABEL: @test_0(
; CHECK-NOT: br
entry:
Index: llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll
+++ llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll
@@ -3,7 +3,7 @@
; Checking that possible users of instruction from the loop in
; unreachable blocks are handled.
-define i64 @foo() {
+define i64 @foo() willreturn {
entry:
br label %invloop
; CHECK-LABEL-NOT: invloop
Index: llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
+++ llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
@@ -216,7 +216,7 @@
; Show recursive deletion of loops. Since we start with subloops and progress outward
; to parent loop, we first delete the loop L2. Now loop L1 becomes a non-loop since it's backedge
; from L2's preheader to L1's exit block is never taken. So, L1 gets deleted as well.
-define void @test8(i64 %n) {
+define void @test8(i64 %n) #0 {
; CHECK-LABEL: test8
; CHECK-LABEL: entry:
; CHECK-NEXT: br label %exit
@@ -318,7 +318,7 @@
; deleted.
; In the next iteration, since L2 is never executed and has no subloops, we delete
; L2 as well. Finally, the outermost loop L1 is deleted.
-define void @test11(i64 %n) {
+define void @test11(i64 %n) #0 {
; CHECK-LABEL: test11
; CHECK-LABEL: entry:
; CHECK-NEXT: br label %exit
@@ -355,7 +355,7 @@
; 2 edges from a single exiting block to the exit block.
-define i64 @test12(i64 %n){
+define i64 @test12(i64 %n) #0 {
;CHECK-LABEL: @test12
; CHECK-NOT: L1:
; CHECK-NOT: L1Latch:
@@ -392,7 +392,7 @@
}
; multiple edges to exit block from the same exiting blocks
-define i64 @test13(i64 %n) {
+define i64 @test13(i64 %n) #0 {
; CHECK-LABEL: @test13
; CHECK-NOT: L1:
; CHECK-NOT: L1Latch:
@@ -433,3 +433,5 @@
%y.phi = phi i64 [ 10, %L1Block ], [ 10, %L1Block ], [ %y.next, %L1 ], [ 30, %L1Latch ], [ 30, %L1Latch ]
ret i64 %y.phi
}
+
+attributes #0 = { willreturn }
Index: llvm/test/Transforms/LoopDeletion/mustprogress.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopDeletion/mustprogress.ll
@@ -0,0 +1,237 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --check-attributes
+; RUN: opt < %s -loop-deletion -S | FileCheck %s
+
+;; Original C Code:
+;; void unknown_tripcount_mustprogress_attr_mustprogress_loopmd(int a, int b) {
+;; for (; a < b;) ;
+;; for (;;) ;
+;; }
+
+define void @unknown_tripcount_mustprogress_attr_mustprogress_loopmd(i32 %a, i32 %b) #0 {
+; CHECK: Function Attrs: mustprogress
+; CHECK-LABEL: define {{[^@]+}}@unknown_tripcount_mustprogress_attr_mustprogress_loopmd
+; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]]) [[ATTR0:#.*]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: unreachable
+;
+entry:
+ br label %for.cond
+for.cond:
+ %cmp = icmp slt i32 %a, %b
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.cond, !llvm.loop !2
+for.end:
+ br label %for.cond1
+for.cond1:
+ br label %for.cond1
+}
+
+;; Original C Code:
+;; void unknown_tripcount_mustprogress_attr_no_mustprogress_loopmd(int a, int b) {
+;; for (; a < b;) ;
+;; for (;;) ;
+;; }
+;; => Removed mustprogress loop attribute
+
+define void @unknown_tripcount_mustprogress_attr_no_mustprogess_loopmd(i32 %a, i32 %b) #0 {
+; CHECK: Function Attrs: mustprogress
+; CHECK-LABEL: define {{[^@]+}}@unknown_tripcount_mustprogress_attr_no_mustprogess_loopmd
+; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]]) [[ATTR0]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: unreachable
+;
+entry:
+ br label %for.cond
+for.cond:
+ %cmp = icmp slt i32 %a, %b
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.cond
+for.end:
+ br label %for.cond1
+for.cond1:
+ br label %for.cond1
+}
+
+;; Original C Code:
+;; void known_tripcount_no_mustprogress_attr_no_mustprogress_loopmd() {
+;; for (int i = 0; i < 5; i++) ;
+;; }
+
+define void @known_tripcount_no_mustprogress_attr_no_mustprogress_loopmd() {
+; CHECK-LABEL: define {{[^@]+}}@known_tripcount_no_mustprogress_attr_no_mustprogress_loopmd() {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.cond
+for.cond:
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+ %cmp = icmp slt i32 %i.0, 5
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.inc
+for.inc:
+ %inc = add nsw i32 %i.0, 1
+ br label %for.cond
+for.end:
+ ret void
+}
+
+;; Original C Code:
+;; void known_tripcount_no_mustprogress_attr_mustprogress_loopmd() {
+;; for (int i = 0; i < 5; i++) ;
+;; }
+;; => Added mustprogress loop attribute
+
+define void @known_tripcount_no_mustprogress_attr_mustprogress_loopmd() {
+; CHECK-LABEL: define {{[^@]+}}@known_tripcount_no_mustprogress_attr_mustprogress_loopmd() {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.cond
+for.cond:
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+ %cmp = icmp slt i32 %i.0, 5
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.inc
+for.inc:
+ %inc = add nsw i32 %i.0, 1
+ br label %for.cond, !llvm.loop !4
+for.end:
+ ret void
+}
+
+;; Original C Code:
+;; void known_tripcount_mustprogress_attr_no_mustprogress_loopmd() {
+;; for (int i = 0; i < 5; i++) ;
+;; }
+;; => Added mustprogress function attribute
+
+define void @known_tripcount_mustprogress_attr_no_mustprogress_loopmd() #0 {
+; CHECK: Function Attrs: mustprogress
+; CHECK-LABEL: define {{[^@]+}}@known_tripcount_mustprogress_attr_no_mustprogress_loopmd
+; CHECK-SAME: () [[ATTR0]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.cond
+for.cond:
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+ %cmp = icmp slt i32 %i.0, 5
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.inc
+for.inc:
+ %inc = add nsw i32 %i.0, 1
+ br label %for.cond
+for.end:
+ ret void
+}
+
+;; Original C Code:
+;; void known_tripcount_mustprogress_attr_mustprogress_loopmd() {
+;; for (int i = 0; i < 5; i++) ;
+;; }
+;; => Added mustprogress function and mustprogress loop attribute
+
+define void @known_tripcount_mustprogress_attr_mustprogress_loopmd() #0 {
+; CHECK: Function Attrs: mustprogress
+; CHECK-LABEL: define {{[^@]+}}@known_tripcount_mustprogress_attr_mustprogress_loopmd
+; CHECK-SAME: () [[ATTR0]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.cond
+for.cond:
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+ %cmp = icmp slt i32 %i.0, 5
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.inc
+for.inc:
+ %inc = add nsw i32 %i.0, 1
+ br label %for.cond, !llvm.loop !5
+for.end:
+ ret void
+}
+
+;; Original C Code:
+;; void unknown_tripcount_no_mustprogress_attr_mustprogress_loopmd(int a, int b) {
+;; for (; a < b;) ;
+;; }
+;; => Added mustprogress loop attribute
+
+define void @unknown_tripcount_no_mustprogress_attr_mustprogress_loopmd(i32 %a, i32 %b) {
+; CHECK-LABEL: define {{[^@]+}}@unknown_tripcount_no_mustprogress_attr_mustprogress_loopmd
+; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]]) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_END:%.*]]
+; CHECK: for.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.cond
+for.cond:
+ %cmp = icmp slt i32 %a, %b
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.cond, !llvm.loop !6
+for.end:
+ ret void
+}
+
+;; Original C Code:
+;; void unknown_tripcount_no_mustprogress_attr_no_mustprogress_loopmd(int a, int b) {
+;; for (; a < b;) ;
+;; }
+
+define void @unknown_tripcount_no_mustprogress_attr_no_mustprogress_loopmd(i32 %a, i32 %b) {
+; CHECK-LABEL: define {{[^@]+}}@unknown_tripcount_no_mustprogress_attr_no_mustprogress_loopmd
+; CHECK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]]) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_COND:%.*]]
+; CHECK: for.cond:
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[A]], [[B]]
+; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY:%.*]], label [[FOR_END:%.*]]
+; CHECK: for.body:
+; CHECK-NEXT: br label [[FOR_COND]]
+; CHECK: for.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.cond
+for.cond:
+ %cmp = icmp slt i32 %a, %b
+ br i1 %cmp, label %for.body, label %for.end
+for.body:
+ br label %for.cond
+for.end:
+ ret void
+}
+
+; CHECK: attributes [[ATTR0]] = { mustprogress }
+
+attributes #0 = { mustprogress }
+!2 = distinct !{!2, !3}
+!3 = !{!"llvm.loop.mustprogress"}
+!4 = distinct !{!4, !3}
+!5 = distinct !{!5, !3}
+!6 = distinct !{!6, !3}
Index: llvm/test/Transforms/LoopDeletion/multiple-exits.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/multiple-exits.ll
+++ llvm/test/Transforms/LoopDeletion/multiple-exits.ll
@@ -10,7 +10,7 @@
; RUN: opt < %s -passes=loop-deletion -S | FileCheck %s --check-prefixes=CHECK,AFTER
-define void @foo(i64 %n, i64 %m) nounwind {
+define void @foo(i64 %n, i64 %m) #0 {
; CHECK-LABEL: @foo(
entry:
@@ -43,7 +43,7 @@
; CHECK-NEXT: ret void
}
-define i64 @bar(i64 %n, i64 %m, i64 %maybe_zero) nounwind {
+define i64 @bar(i64 %n, i64 %m, i64 %maybe_zero) #0 {
; CHECK-LABEL: @bar(
entry:
@@ -95,7 +95,7 @@
; This function has a loop which looks like @bar's but that cannot be deleted
; because which path we exit through determines which value is selected.
-define i64 @baz(i64 %n, i64 %m, i64 %maybe_zero) nounwind {
+define i64 @baz(i64 %n, i64 %m, i64 %maybe_zero) #0 {
; CHECK-LABEL: @baz(
entry:
@@ -136,3 +136,5 @@
; CHECK-NEXT: %[[X:.*]] = phi i64 [ 12, %bb ], [ 10, %bb2 ], [ 10, %bb3 ]
; CHECK-NEXT: ret i64 %[[X]]
}
+
+attributes #0 = { nounwind willreturn }
\ No newline at end of file
Index: llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll
+++ llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll
@@ -11,7 +11,7 @@
; CHECK: return:
; CHECK-NEXT: ret void
-define void @foo(i64 %n, i64 %m) nounwind {
+define void @foo(i64 %n, i64 %m) nounwind willreturn {
entry:
br label %bb
Index: llvm/test/Transforms/LoopDeletion/invalidation.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/invalidation.ll
+++ llvm/test/Transforms/LoopDeletion/invalidation.ll
@@ -8,7 +8,7 @@
; RUN: | FileCheck %s --check-prefixes=CHECK,AFTER
-define void @foo(i64 %n, i64 %m) nounwind {
+define void @foo(i64 %n, i64 %m) nounwind willreturn {
; CHECK-LABEL: @foo(
entry:
Index: llvm/test/Transforms/LoopDeletion/diundef.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/diundef.ll
+++ llvm/test/Transforms/LoopDeletion/diundef.ll
@@ -5,7 +5,7 @@
@a = common local_unnamed_addr global i32 0, align 4, !dbg !0
-define i32 @b() local_unnamed_addr !dbg !12 {
+define i32 @b() local_unnamed_addr willreturn !dbg !12 {
entry:
call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !DIExpression()), !dbg !17
br label %for.cond, !dbg !18
Index: llvm/test/Transforms/LoopDeletion/basic-remark.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/basic-remark.ll
+++ llvm/test/Transforms/LoopDeletion/basic-remark.ll
@@ -10,7 +10,7 @@
; CHECK-NEXT: Args:
; CHECK-NEXT: - String: Loop deleted because it is invariant
; CHECK-NEXT: ...
-define i32 @main() local_unnamed_addr #0 {
+define i32 @main() local_unnamed_addr willreturn {
entry:
br label %for.cond, !dbg !9
Index: llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
+++ llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
@@ -14,7 +14,7 @@
; DT: [3] %for.body
; DT: [4] %for.cond3.loopexit
-define i32 @fn1() {
+define i32 @fn1() willreturn {
entry:
br label %for.cond
Index: llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll
===================================================================
--- llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll
+++ llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll
@@ -6,7 +6,7 @@
; RUN: opt < %s -licm -loop-deletion -simplifycfg -S | \
; RUN: not grep "br "
-define i32 @main(i32 %argc) {
+define i32 @main(i32 %argc) willreturn {
; <label>:0
br label %bb5
bb5: ; preds = %bb5, %0
Index: llvm/test/Other/loop-pm-invalidation.ll
===================================================================
--- llvm/test/Other/loop-pm-invalidation.ll
+++ llvm/test/Other/loop-pm-invalidation.ll
@@ -227,7 +227,7 @@
ret void
}
-define void @dead_loop() {
+define void @dead_loop() willreturn {
; CHECK-LOOP-INV: Starting {{.*}}Function pass manager run
; CHECK-LOOP-INV-NEXT: Starting {{.*}}Function pass manager run
; CHECK-LOOP-INV-NEXT: Running pass: LoopSimplifyPass
Index: llvm/test/Other/loop-deletion-printer.ll
===================================================================
--- llvm/test/Other/loop-deletion-printer.ll
+++ llvm/test/Other/loop-deletion-printer.ll
@@ -14,7 +14,7 @@
; DELETED-BUT-PRINTED: IR Dump {{.*}}LoopDeletionPass {{.*invalidated:}}
; DELETED-BUT-PRINTED-NOT: IR Dump {{.*}}LoopInstSimplifyPass
-define void @deleteme() {
+define void @deleteme() willreturn {
entry:
br label %loop
loop:
Index: llvm/lib/Transforms/Utils/LoopUtils.cpp
===================================================================
--- llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -63,6 +63,7 @@
static const char *LLVMLoopDisableNonforced = "llvm.loop.disable_nonforced";
static const char *LLVMLoopDisableLICM = "llvm.licm.disable";
+static const char *LLVMLoopMustProgress = "llvm.loop.mustprogress";
bool llvm::formDedicatedExitBlocks(Loop *L, DominatorTree *DT, LoopInfo *LI,
MemorySSAUpdater *MSSAU,
@@ -404,6 +405,10 @@
return getBooleanLoopAttribute(L, LLVMLoopDisableLICM);
}
+bool llvm::hasMustProgress(const Loop *L) {
+ return getBooleanLoopAttribute(L, LLVMLoopMustProgress);
+}
+
TransformationMode llvm::hasUnrollTransformation(Loop *L) {
if (getBooleanLoopAttribute(L, "llvm.loop.unroll.disable"))
return TM_SuppressedByUser;
@@ -542,10 +547,6 @@
if (SE)
SE->forgetLoop(L);
- auto *ExitBlock = L->getUniqueExitBlock();
- assert(ExitBlock && "Should have a unique exit block!");
- assert(L->hasDedicatedExits() && "Loop should have dedicated exits!");
-
auto *OldBr = dyn_cast<BranchInst>(Preheader->getTerminator());
assert(OldBr && "Preheader must end with a branch");
assert(OldBr->isUnconditional() && "Preheader must have a single successor");
@@ -575,59 +576,73 @@
// deleting the backedge of the outer loop). If the outer loop is indeed a
// non-loop, it will be deleted in a future iteration of loop deletion pass.
IRBuilder<> Builder(OldBr);
- Builder.CreateCondBr(Builder.getFalse(), L->getHeader(), ExitBlock);
- // Remove the old branch. The conditional branch becomes a new terminator.
- OldBr->eraseFromParent();
-
- // Rewrite phis in the exit block to get their inputs from the Preheader
- // instead of the exiting block.
- for (PHINode &P : ExitBlock->phis()) {
- // Set the zero'th element of Phi to be from the preheader and remove all
- // other incoming values. Given the loop has dedicated exits, all other
- // incoming values must be from the exiting blocks.
- int PredIndex = 0;
- P.setIncomingBlock(PredIndex, Preheader);
- // Removes all incoming values from all other exiting blocks (including
- // duplicate values from an exiting block).
- // Nuke all entries except the zero'th entry which is the preheader entry.
- // NOTE! We need to remove Incoming Values in the reverse order as done
- // below, to keep the indices valid for deletion (removeIncomingValues
- // updates getNumIncomingValues and shifts all values down into the operand
- // being deleted).
- for (unsigned i = 0, e = P.getNumIncomingValues() - 1; i != e; ++i)
- P.removeIncomingValue(e - i, false);
-
- assert((P.getNumIncomingValues() == 1 &&
- P.getIncomingBlock(PredIndex) == Preheader) &&
- "Should have exactly one value and that's from the preheader!");
- }
- DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
- if (DT) {
- DTU.applyUpdates({{DominatorTree::Insert, Preheader, ExitBlock}});
- if (MSSA) {
- MSSAU->applyUpdates({{DominatorTree::Insert, Preheader, ExitBlock}}, *DT);
- if (VerifyMemorySSA)
- MSSA->verifyMemorySSA();
+ auto *ExitBlock = L->getUniqueExitBlock();
+ if (L->getNumExitBlocks() == 0) {
+ // If this loop does not have an exit block, we can still remove the loop
+ // and replace the Preheader with an Unreachable.
+ Builder.SetInsertPoint(OldBr);
+ Builder.CreateUnreachable();
+ Preheader->getTerminator()->eraseFromParent();
+ } else {
+ assert(ExitBlock && "Should have a unique exit block!");
+ assert(L->hasDedicatedExits() && "Loop should have dedicated exits!");
+
+ Builder.CreateCondBr(Builder.getFalse(), L->getHeader(), ExitBlock);
+ // Remove the old branch. The conditional branch becomes a new terminator.
+ OldBr->eraseFromParent();
+
+ // Rewrite phis in the exit block to get their inputs from the Preheader
+ // instead of the exiting block.
+ for (PHINode &P : ExitBlock->phis()) {
+ // Set the zero'th element of Phi to be from the preheader and remove all
+ // other incoming values. Given the loop has dedicated exits, all other
+ // incoming values must be from the exiting blocks.
+ int PredIndex = 0;
+ P.setIncomingBlock(PredIndex, Preheader);
+ // Removes all incoming values from all other exiting blocks (including
+ // duplicate values from an exiting block).
+ // Nuke all entries except the zero'th entry which is the preheader entry.
+ // NOTE! We need to remove Incoming Values in the reverse order as done
+ // below, to keep the indices valid for deletion (removeIncomingValues
+ // updates getNumIncomingValues and shifts all values down into the
+ // operand being deleted).
+ for (unsigned i = 0, e = P.getNumIncomingValues() - 1; i != e; ++i)
+ P.removeIncomingValue(e - i, false);
+
+ assert((P.getNumIncomingValues() == 1 &&
+ P.getIncomingBlock(PredIndex) == Preheader) &&
+ "Should have exactly one value and that's from the preheader!");
+ }
+
+ DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
+ if (DT) {
+ DTU.applyUpdates({{DominatorTree::Insert, Preheader, ExitBlock}});
+ if (MSSA) {
+ MSSAU->applyUpdates({{DominatorTree::Insert, Preheader, ExitBlock}},
+ *DT);
+ if (VerifyMemorySSA)
+ MSSA->verifyMemorySSA();
+ }
}
- }
- // Disconnect the loop body by branching directly to its exit.
- Builder.SetInsertPoint(Preheader->getTerminator());
- Builder.CreateBr(ExitBlock);
- // Remove the old branch.
- Preheader->getTerminator()->eraseFromParent();
-
- if (DT) {
- DTU.applyUpdates({{DominatorTree::Delete, Preheader, L->getHeader()}});
- if (MSSA) {
- MSSAU->applyUpdates({{DominatorTree::Delete, Preheader, L->getHeader()}},
- *DT);
- SmallSetVector<BasicBlock *, 8> DeadBlockSet(L->block_begin(),
- L->block_end());
- MSSAU->removeBlocks(DeadBlockSet);
- if (VerifyMemorySSA)
- MSSA->verifyMemorySSA();
+ // Disconnect the loop body by branching directly to its exit.
+ Builder.SetInsertPoint(Preheader->getTerminator());
+ Builder.CreateBr(ExitBlock);
+ // Remove the old branch.
+ Preheader->getTerminator()->eraseFromParent();
+
+ if (DT) {
+ DTU.applyUpdates({{DominatorTree::Delete, Preheader, L->getHeader()}});
+ if (MSSA) {
+ MSSAU->applyUpdates(
+ {{DominatorTree::Delete, Preheader, L->getHeader()}}, *DT);
+ SmallSetVector<BasicBlock *, 8> DeadBlockSet(L->block_begin(),
+ L->block_end());
+ MSSAU->removeBlocks(DeadBlockSet);
+ if (VerifyMemorySSA)
+ MSSA->verifyMemorySSA();
+ }
}
}
@@ -674,15 +689,17 @@
// Since debug values in the loop have been deleted, inserting an undef
// dbg.value truncates the range of any dbg.value before the loop where the
// loop used to be. This is particularly important for constant values.
- DIBuilder DIB(*ExitBlock->getModule());
- Instruction *InsertDbgValueBefore = ExitBlock->getFirstNonPHI();
- assert(InsertDbgValueBefore &&
- "There should be a non-PHI instruction in exit block, else these "
- "instructions will have no parent.");
- for (auto *DVI : DeadDebugInst)
- DIB.insertDbgValueIntrinsic(UndefValue::get(Builder.getInt32Ty()),
- DVI->getVariable(), DVI->getExpression(),
- DVI->getDebugLoc(), InsertDbgValueBefore);
+ if (ExitBlock) {
+ DIBuilder DIB(*ExitBlock->getModule());
+ Instruction *InsertDbgValueBefore = ExitBlock->getFirstNonPHI();
+ assert(InsertDbgValueBefore &&
+ "There should be a non-PHI instruction in exit block, else these "
+ "instructions will have no parent.");
+ for (auto *DVI : DeadDebugInst)
+ DIB.insertDbgValueIntrinsic(UndefValue::get(Builder.getInt32Ty()),
+ DVI->getVariable(), DVI->getExpression(),
+ DVI->getDebugLoc(), InsertDbgValueBefore);
+ }
// Remove the block from the reference counting scheme, so that we can
// delete it freely later.
Index: llvm/lib/Transforms/Scalar/LoopDeletion.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -53,26 +53,28 @@
// of the loop.
bool AllEntriesInvariant = true;
bool AllOutgoingValuesSame = true;
- for (PHINode &P : ExitBlock->phis()) {
- Value *incoming = P.getIncomingValueForBlock(ExitingBlocks[0]);
-
- // Make sure all exiting blocks produce the same incoming value for the exit
- // block. If there are different incoming values for different exiting
- // blocks, then it is impossible to statically determine which value should
- // be used.
- AllOutgoingValuesSame =
- all_of(makeArrayRef(ExitingBlocks).slice(1), [&](BasicBlock *BB) {
- return incoming == P.getIncomingValueForBlock(BB);
- });
-
- if (!AllOutgoingValuesSame)
- break;
-
- if (Instruction *I = dyn_cast<Instruction>(incoming))
- if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator())) {
- AllEntriesInvariant = false;
+ if (L->getNumExitBlocks() != 0) {
+ for (PHINode &P : ExitBlock->phis()) {
+ Value *incoming = P.getIncomingValueForBlock(ExitingBlocks[0]);
+
+ // Make sure all exiting blocks produce the same incoming value for the
+ // exit block. If there are different incoming values for different
+ // exiting blocks, then it is impossible to statically determine which
+ // value should be used.
+ AllOutgoingValuesSame =
+ all_of(makeArrayRef(ExitingBlocks).slice(1), [&](BasicBlock *BB) {
+ return incoming == P.getIncomingValueForBlock(BB);
+ });
+
+ if (!AllOutgoingValuesSame)
break;
- }
+
+ if (Instruction *I = dyn_cast<Instruction>(incoming))
+ if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator())) {
+ AllEntriesInvariant = false;
+ break;
+ }
+ }
}
if (Changed)
@@ -193,7 +195,7 @@
// be in the situation of needing to be able to solve statically which exit
// block will be branched to, or trying to preserve the branching logic in
// a loop invariant manner.
- if (!ExitBlock) {
+ if (!ExitBlock && L->getNumExitBlocks() != 0) {
LLVM_DEBUG(dbgs() << "Deletion requires single exit block\n");
return LoopDeletionResult::Unmodified;
}
@@ -208,8 +210,10 @@
// Don't remove loops for which we can't solve the trip count.
// They could be infinite, in which case we'd be changing program behavior.
const SCEV *S = SE.getConstantMaxBackedgeTakenCount(L);
- if (isa<SCEVCouldNotCompute>(S)) {
- LLVM_DEBUG(dbgs() << "Could not compute SCEV MaxBackedgeTakenCount.\n");
+ if (isa<SCEVCouldNotCompute>(S) &&
+ !L->getHeader()->getParent()->mustProgress() && !hasMustProgress(L)) {
+ LLVM_DEBUG(dbgs() << "Could not compute SCEV MaxBackedgeTakenCount and was "
+ "not required to make progress.\n");
return Changed ? LoopDeletionResult::Modified
: LoopDeletionResult::Unmodified;
}
Index: llvm/include/llvm/Transforms/Utils/LoopUtils.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/LoopUtils.h
+++ llvm/include/llvm/Transforms/Utils/LoopUtils.h
@@ -229,6 +229,9 @@
/// Look for the loop attribute that disables the LICM transformation heuristics.
bool hasDisableLICMTransformsHint(const Loop *L);
+/// Look for the loop attribute that requires progress within the loop.
+bool hasMustProgress(const Loop *L);
+
/// The mode sets how eager a transformation should be applied.
enum TransformationMode {
/// The pass can use heuristics to determine whether a transformation should
Index: llvm/include/llvm/Analysis/LoopInfoImpl.h
===================================================================
--- llvm/include/llvm/Analysis/LoopInfoImpl.h
+++ llvm/include/llvm/Analysis/LoopInfoImpl.h
@@ -135,6 +135,13 @@
return nullptr;
}
+template <class BlockT, class LoopT>
+unsigned LoopBase<BlockT, LoopT>::getNumExitBlocks() const {
+ SmallVector<BlockT *, 8> UniqueExitBlocks;
+ getUniqueExitBlocks(UniqueExitBlocks);
+ return UniqueExitBlocks.size();
+}
+
/// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
template <class BlockT, class LoopT>
void LoopBase<BlockT, LoopT>::getExitEdges(
Index: llvm/include/llvm/Analysis/LoopInfo.h
===================================================================
--- llvm/include/llvm/Analysis/LoopInfo.h
+++ llvm/include/llvm/Analysis/LoopInfo.h
@@ -302,6 +302,8 @@
/// Otherwise return null.
BlockT *getUniqueExitBlock() const;
+ unsigned getNumExitBlocks() const;
+
/// Edge type.
typedef std::pair<BlockT *, BlockT *> Edge;
Index: clang/test/Misc/loop-opt-setup.c
===================================================================
--- clang/test/Misc/loop-opt-setup.c
+++ clang/test/Misc/loop-opt-setup.c
@@ -23,8 +23,8 @@
--num_active;
}
-// Check br i1 to make sure the loop is gone, there will still be a label branch for the infinite loop.
+// Check br i1 to make sure the loop is gone, there will be no loop here.
// CHECK-LABEL: Helper
-// CHECK: br label
+// CHECK: entry:
// CHECK-NOT: br i1
-// CHECK: br label
+// CHECK-NEXT: ret void
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