[PATCH] D37215: [ValueTracking] improve reverse assumption inference

[Nikita Popov via Phabricator via llvm-commits]

nikic updated this revision to Diff 209735.
nikic added a comment.

Rebase over baseline tests.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D37215/new/

https://reviews.llvm.org/D37215

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/InstCombine/assume_inevitable.ll


Index: llvm/test/Transforms/InstCombine/assume_inevitable.ll
===================================================================
--- llvm/test/Transforms/InstCombine/assume_inevitable.ll
+++ llvm/test/Transforms/InstCombine/assume_inevitable.ll
@@ -8,10 +8,10 @@
 ; CHECK-LABEL: @assume_inevitable(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[M:%.*]] = alloca i64, align 8
-; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[A:%.*]], align 4
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[A:%.*]], align 32
 ; CHECK-NEXT:    [[LOADRES:%.*]] = load i32, i32* [[B:%.*]], align 4
 ; CHECK-NEXT:    [[LOADRES2:%.*]] = call i32 @llvm.annotation.i32(i32 [[LOADRES]], i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str1, i64 0, i64 0), i32 2)
-; CHECK-NEXT:    store i32 [[LOADRES2]], i32* [[A]], align 4
+; CHECK-NEXT:    store i32 [[LOADRES2]], i32* [[A]], align 32
 ; CHECK-NEXT:    [[DUMMY_EQ:%.*]] = icmp ugt i32 [[LOADRES]], 42
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[DUMMY_EQ]])
 ; CHECK-NEXT:    [[M_I8:%.*]] = bitcast i64* [[M]] to i8*
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -514,8 +514,10 @@
       case Intrinsic::lifetime_start:
       case Intrinsic::lifetime_end:
       case Intrinsic::objectsize:
+      case Intrinsic::annotation:
       case Intrinsic::ptr_annotation:
       case Intrinsic::var_annotation:
+      case Intrinsic::experimental_widenable_condition:
         return true;
       }
 
@@ -558,12 +560,18 @@
         return true;
   }
 
+  // Don't let an assume affect itself - this would cause the problems
+  // `isEphemeralValueOf` is trying to prevent, and it would also make
+  // the loop below go out of bounds.
+  if (Inv == CxtI)
+    return false;
+
   // The context comes first, but they're both in the same block. Make sure
   // there is nothing in between that might interrupt the control flow.
   for (BasicBlock::const_iterator I =
          std::next(BasicBlock::const_iterator(CxtI)), IE(Inv);
        I != IE; ++I)
-    if (!isSafeToSpeculativelyExecute(&*I) && !isAssumeLikeIntrinsic(&*I))
+    if (!isGuaranteedToTransferExecutionToSuccessor(&*I))
       return false;
 
   return !isEphemeralValueOf(Inv, CxtI);
@@ -4268,9 +4276,7 @@
     // FIXME: This isn't aggressive enough; a call which only writes to a global
     // is guaranteed to return.
     return CS.onlyReadsMemory() || CS.onlyAccessesArgMemory() ||
-           match(I, m_Intrinsic<Intrinsic::assume>()) ||
-           match(I, m_Intrinsic<Intrinsic::sideeffect>()) ||
-           match(I, m_Intrinsic<Intrinsic::experimental_widenable_condition>());
+           isAssumeLikeIntrinsic(I);
   }
 
   // Other instructions return normally.


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