atmnpatel updated this revision to Diff 313484.
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https://reviews.llvm.org/D86844/new/
https://reviews.llvm.org/D86844
Files:
clang/test/Misc/loop-opt-setup.c
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/no-exit-blocks.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/no-exit-blocks.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/no-exit-blocks.ll
+++ llvm/test/Transforms/LoopDeletion/no-exit-blocks.ll
@@ -5,14 +5,7 @@
; CHECK: Function Attrs: mustprogress
; CHECK-LABEL: define {{[^@]+}}@f
; CHECK-SAME: () [[ATTR0:#.*]] {
-; CHECK-NEXT: br label [[TMP1:%.*]]
-; CHECK: 1:
-; CHECK-NEXT: [[DOT01:%.*]] = phi i32 [ 1, [[TMP0:%.*]] ], [ [[TMP3:%.*]], [[TMP2:%.*]] ]
-; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 1, [[TMP0]] ], [ [[TMP3]], [[TMP2]] ]
-; CHECK-NEXT: br label [[TMP2]]
-; CHECK: 2:
-; CHECK-NEXT: [[TMP3]] = add nsw i32 [[DOT01]], [[DOT0]]
-; CHECK-NEXT: br label [[TMP1]]
+; CHECK-NEXT: unreachable
;
br label %1
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
@@ -15,7 +15,7 @@
; 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 -simplifycfg-require-and-preserve-domtree=1 -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,
@@ -419,6 +420,10 @@
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;
@@ -589,6 +594,7 @@
IRBuilder<> Builder(OldBr);
auto *ExitBlock = L->getUniqueExitBlock();
+ DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
if (ExitBlock) {
assert(ExitBlock && "Should have a unique exit block!");
assert(L->hasDedicatedExits() && "Loop should have dedicated exits!");
@@ -620,7 +626,6 @@
"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) {
@@ -636,27 +641,28 @@
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();
- }
- }
} else {
assert(L->hasNoExitBlocks() &&
"Loop should have either zero or one exit blocks.");
+
Builder.SetInsertPoint(OldBr);
Builder.CreateUnreachable();
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();
+ }
+ }
+
// Use a map to unique and a vector to guarantee deterministic ordering.
llvm::SmallDenseSet<std::pair<DIVariable *, DIExpression *>, 4> DeadDebugSet;
llvm::SmallVector<DbgVariableIntrinsic *, 4> DeadDebugInst;
Index: llvm/lib/Transforms/Scalar/LoopDeletion.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -128,10 +128,11 @@
/// Remove a loop if it is dead.
///
-/// A loop is considered dead if it does not impact the observable behavior of
-/// the program other than finite running time. This never removes a loop that
-/// might be infinite (unless it is never executed), as doing so could change
-/// the halting/non-halting nature of a program.
+/// A loop is considered dead either if it does not impact the observable
+/// behavior of the program other than finite running time, or if it is
+/// required to make progress by an attribute such as 'mustprogress' or
+/// 'llvm.loop.mustprogress' and does not make any. This may remove
+/// infinite loops that have been required to make progress.
///
/// This entire process relies pretty heavily on LoopSimplify form and LCSSA in
/// order to make various safety checks work.
@@ -207,11 +208,13 @@
: LoopDeletionResult::Unmodified;
}
- // 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.
+ // Don't remove loops for which we can't solve the trip count unless the loop
+ // was required to make progress but has been determined to be dead.
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
@@ -255,6 +255,9 @@
/// 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: clang/test/Misc/loop-opt-setup.c
===================================================================
--- clang/test/Misc/loop-opt-setup.c
+++ clang/test/Misc/loop-opt-setup.c
@@ -1,4 +1,5 @@
// RUN: %clang -O1 -fno-unroll-loops -S -o - %s -emit-llvm | FileCheck %s
+// RUN: %clang -std=c99 -O1 -fno-unroll-loops -S -o - %s -emit-llvm | FileCheck %s --check-prefix C99
extern int a[16];
int b = 0;
@@ -25,6 +26,9 @@
// Check br i1 to make sure the loop is gone, there will still be a label branch for the infinite loop.
// CHECK-LABEL: Helper
-// CHECK: br label
-// CHECK-NOT: br i1
-// CHECK: br label
+// C99: br label
+// C99-NOT: br i1
+// C99: br label
+// CHECK: entry:
+// CHECK-NOT: br i1
+// CHECK-NEXT: ret void
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