[LoopDeletion] Allows deletion of possibly infinite side-effect free loops

From C11 and C++11 onwards, a forward-progress requirement has been
introduced for both languages. In the case of C, loops with non-constant
conditionals that do not have any observable side-effects (as defined by
6.8.5p6) can be assumed by the implementation to terminate, and in the
case of C++, this assumption extends to all functions. The clang
frontend will emit the `mustprogress` function attribute for C++
functions (D86233, D85393, D86841) and emit the loop metadata
`llvm.loop.mustprogress` for every loop in C11 or later that has a
non-constant conditional.

This patch modifies LoopDeletion so that only loops with
the `llvm.loop.mustprogress` metadata or loops contained in functions
that are required to make progress (`mustprogress` or `willreturn`) are
checked for observable side-effects. If these loops do not have an
observable side-effect, then we delete them.

Loops without observable side-effects that do not satisfy the above
conditions will not be deleted.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D86844

diff --git a/clang/test/Misc/loop-opt-setup.c b/clang/test/Misc/loop-opt-setup.c
index 322f5e0..43a9f85 100644 (file)
--- a/clang/test/Misc/loop-opt-setup.c
+++ b/clang/test/Misc/loop-opt-setup.c
@@ -25,6 +25,6 @@ void Helper() {
 
 // 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: entry:
 // CHECK-NOT: br i1
-// CHECK: br label
+// CHECK-NEXT: ret void

diff --git a/llvm/include/llvm/Transforms/Utils/LoopUtils.h b/llvm/include/llvm/Transforms/Utils/LoopUtils.h
index d741b51..076ea2f 100644 (file)
--- a/llvm/include/llvm/Transforms/Utils/LoopUtils.h
+++ b/llvm/include/llvm/Transforms/Utils/LoopUtils.h
@@ -229,6 +229,9 @@ bool hasDisableAllTransformsHint(const Loop *L);
 /// 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

diff --git a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
index 065db64..0db50d0 100644 (file)
--- a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -210,8 +210,10 @@ static LoopDeletionResult deleteLoopIfDead(Loop *L, DominatorTree &DT,
   // 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;
   }

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index e10a230..4210cd6 100644 (file)
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -63,6 +63,7 @@ static cl::opt<bool> ForceReductionIntrinsic(
 
 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 @@ bool llvm::hasDisableLICMTransformsHint(const Loop *L) {
   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;

diff --git a/llvm/test/Other/loop-deletion-printer.ll b/llvm/test/Other/loop-deletion-printer.ll
index 6cb29ae..9979051 100644 (file)
--- a/llvm/test/Other/loop-deletion-printer.ll
+++ b/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:

diff --git a/llvm/test/Other/loop-pm-invalidation.ll b/llvm/test/Other/loop-pm-invalidation.ll
index 9deb17f..e6bd888 100644 (file)
--- a/llvm/test/Other/loop-pm-invalidation.ll
+++ b/llvm/test/Other/loop-pm-invalidation.ll
@@ -227,7 +227,7 @@ exit:
   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

diff --git a/llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll b/llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll
index b54d520..8ff3221 100644 (file)
--- a/llvm/test/Transforms/LICM/2003-02-27-PreheaderProblem.ll
+++ b/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

diff --git a/llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll b/llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
index ad8b8b4..ca1b2ec 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
+++ b/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
 

diff --git a/llvm/test/Transforms/LoopDeletion/basic-remark.ll b/llvm/test/Transforms/LoopDeletion/basic-remark.ll
index c56ae9d..757bb78 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/basic-remark.ll
+++ b/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
 

diff --git a/llvm/test/Transforms/LoopDeletion/diundef.ll b/llvm/test/Transforms/LoopDeletion/diundef.ll
index 11dc05c..1245ed5 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/diundef.ll
+++ b/llvm/test/Transforms/LoopDeletion/diundef.ll
@@ -5,7 +5,7 @@ target triple = "x86_64-apple-macosx10.14.0"
 
 @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

diff --git a/llvm/test/Transforms/LoopDeletion/invalidation.ll b/llvm/test/Transforms/LoopDeletion/invalidation.ll
index 3f73526..d010f03 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/invalidation.ll
+++ b/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:

diff --git a/llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll b/llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll
index e7b4721..7231e92 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/multiple-exit-conditions.ll
+++ b/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
 

diff --git a/llvm/test/Transforms/LoopDeletion/multiple-exits.ll b/llvm/test/Transforms/LoopDeletion/multiple-exits.ll
index 760c3aa..d418b64 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/multiple-exits.ll
+++ b/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 @@ return:
 ; 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 @@ return:
 
 ; 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 @@ return:
 ; 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

diff --git a/llvm/test/Transforms/LoopDeletion/mustprogress.ll b/llvm/test/Transforms/LoopDeletion/mustprogress.ll
new file mode 100644 (file)
index 0000000..d94fdb4
--- /dev/null
+++ b/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}

diff --git a/llvm/test/Transforms/LoopDeletion/no-exit-blocks.ll b/llvm/test/Transforms/LoopDeletion/no-exit-blocks.ll
index cd79090..1e68d4f 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/no-exit-blocks.ll
+++ b/llvm/test/Transforms/LoopDeletion/no-exit-blocks.ll
@@ -5,14 +5,7 @@ define void @f() #0 {
 ; 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
 

diff --git a/llvm/test/Transforms/LoopDeletion/unreachable-loops.ll b/llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
index a74ddf9..d4a80b9 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
+++ b/llvm/test/Transforms/LoopDeletion/unreachable-loops.ll
@@ -216,7 +216,7 @@ exit:
 ; 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 @@ exit:
 ; 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 @@ exit:
 
 
 ; 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 @@ exit:                                             ; preds = %L1Latch, %L1Latch
 }
 
 ; 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 @@ exit:                                             ; preds = %L1Block, %L1, %L1La
   %y.phi = phi i64 [ 10, %L1Block ], [ 10, %L1Block ], [ %y.next, %L1 ], [ 30, %L1Latch ], [ 30, %L1Latch ]
   ret i64 %y.phi
 }
+
+attributes #0 = { willreturn }

diff --git a/llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll b/llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll
index ff7bc75..3e06e18 100644 (file)
--- a/llvm/test/Transforms/LoopDeletion/use-in-unreachable.ll
+++ b/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

diff --git a/llvm/test/Transforms/SCCP/calltest.ll b/llvm/test/Transforms/SCCP/calltest.ll
index a6c2606..bd49b45 100644 (file)
--- a/llvm/test/Transforms/SCCP/calltest.ll
+++ b/llvm/test/Transforms/SCCP/calltest.ll
@@ -4,7 +4,7 @@ declare double @sqrt(double) readnone nounwind
 %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:

diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll b/llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll
index e8e34a2..ea6d0e5 100644 (file)
--- a/llvm/test/Transforms/SimpleLoopUnswitch/pr37888.ll
+++ b/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