Revert "[LoopDeletion] Allows deletion of possibly infinite side-effe…

…ct free loops" This reverts commit 0b17c6e. This patch causes a compile-time error in SCEV.
llvm · Nov 7, 2020 · 04a0896 · 04a0896
1 parent d3e75d3
commit 04a0896
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Showing 18 changed files with 28 additions and 272 deletions.
diff --git a/llvm/include/llvm/Transforms/Utils/LoopUtils.h b/llvm/include/llvm/Transforms/Utils/LoopUtils.h
@@ -229,9 +229,6 @@ 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
@@ -210,10 +210,8 @@ 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) &&
-      !L->getHeader()->getParent()->mustProgress() && !hasMustProgress(L)) {
-    LLVM_DEBUG(dbgs() << "Could not compute SCEV MaxBackedgeTakenCount and was "
-                         "not required to make progress.\n");
+  if (isa<SCEVCouldNotCompute>(S)) {
+    LLVM_DEBUG(dbgs() << "Could not compute SCEV MaxBackedgeTakenCount.\n");
     return Changed ? LoopDeletionResult::Modified
                    : LoopDeletionResult::Unmodified;
   }

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -63,7 +63,6 @@ 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,
@@ -405,10 +404,6 @@ 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
@@ -14,7 +14,7 @@
 ; DELETED-BUT-PRINTED: IR Dump {{.*}}LoopDeletionPass {{.*invalidated:}}
 ; DELETED-BUT-PRINTED-NOT: IR Dump {{.*}}LoopInstSimplifyPass
 
-define void @deleteme() willreturn {
+define void @deleteme() {
 entry:
   br label %loop
 loop:

diff --git 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() willreturn {
+define void @dead_loop() {
 ; 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
@@ -6,7 +6,7 @@
 ; RUN: opt < %s -licm -loop-deletion -simplifycfg -S | \
 ; RUN:   not grep "br "
 
-define i32 @main(i32 %argc) willreturn {
+define i32 @main(i32 %argc) {
 ; <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
@@ -15,7 +15,7 @@
 ; DT:     [3] %for.body
 ; DT:       [4] %for.cond3.loopexit
 
-define i32 @fn1() willreturn {
+define i32 @fn1() {
 entry:
   br label %for.cond
 

diff --git 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 willreturn {
+define i32 @main() local_unnamed_addr #0 {
 entry:
   br label %for.cond, !dbg !9
 

diff --git 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 willreturn !dbg !12 {
+define i32 @b() local_unnamed_addr !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
@@ -8,7 +8,7 @@
 ; RUN:     | FileCheck %s --check-prefixes=CHECK,AFTER
 
 
-define void @foo(i64 %n, i64 %m) nounwind willreturn {
+define void @foo(i64 %n, i64 %m) nounwind {
 ; CHECK-LABEL: @foo(
 
 entry:

diff --git 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 willreturn {
+define void @foo(i64 %n, i64 %m) nounwind {
 entry:
   br label %bb
 

diff --git 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) #0 {
+define void @foo(i64 %n, i64 %m) nounwind {
 ; CHECK-LABEL: @foo(
 
 entry:
@@ -43,7 +43,7 @@ return:
 ; CHECK-NEXT:    ret void
 }
 
-define i64 @bar(i64 %n, i64 %m, i64 %maybe_zero) #0 {
+define i64 @bar(i64 %n, i64 %m, i64 %maybe_zero) nounwind {
 ; 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) #0 {
+define i64 @baz(i64 %n, i64 %m, i64 %maybe_zero) nounwind {
 ; CHECK-LABEL:  @baz(
 
 entry:
@@ -136,5 +136,3 @@ return:
 ; CHECK-NEXT:  %[[X:.*]] = phi i64 [ 12, %bb ], [ 10, %bb2 ], [ 10, %bb3 ]
 ; CHECK-NEXT:  ret i64 %[[X]]
 }
-
-attributes #0 = { nounwind willreturn }
diff --git a/llvm/test/Transforms/LoopDeletion/mustprogress.ll b/llvm/test/Transforms/LoopDeletion/mustprogress.ll