[llvm] 2e9bc1b - [LVI] Use !range metadata for supported intrinsics

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-01-26T15:09:48+01:00
New Revision: 2e9bc1b8614c9422573cf2f4728525787b0cb0cb

URL: https://github.com/llvm/llvm-project/commit/2e9bc1b8614c9422573cf2f4728525787b0cb0cb
DIFF: https://github.com/llvm/llvm-project/commit/2e9bc1b8614c9422573cf2f4728525787b0cb0cb.diff

LOG: [LVI] Use !range metadata for supported intrinsics

Even if the intrinsic is supported by ConstantRange, we should
still make use of !range metadata. This doesn't matter much now,
but is important if we want to support ctlz style intrinsics,
which always have KnownBits-based !range metadata attached, which
might be better than what we can compute using ranges.

Added: 
    

Modified: 
    llvm/lib/Analysis/LazyValueInfo.cpp
    llvm/test/Transforms/CorrelatedValuePropagation/range.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index f1587cecf9fbd..16d9ad74769ea 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -990,10 +990,11 @@ LazyValueInfoImpl::solveBlockValueOverflowIntrinsic(WithOverflowInst *WO,
 
 std::optional<ValueLatticeElement>
 LazyValueInfoImpl::solveBlockValueIntrinsic(IntrinsicInst *II, BasicBlock *BB) {
+  ValueLatticeElement MetadataVal = getFromRangeMetadata(II);
   if (!ConstantRange::isIntrinsicSupported(II->getIntrinsicID())) {
     LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()
                       << "' - unknown intrinsic.\n");
-    return getFromRangeMetadata(II);
+    return MetadataVal;
   }
 
   SmallVector<ConstantRange, 2> OpRanges;
@@ -1004,8 +1005,9 @@ LazyValueInfoImpl::solveBlockValueIntrinsic(IntrinsicInst *II, BasicBlock *BB) {
     OpRanges.push_back(*Range);
   }
 
-  return ValueLatticeElement::getRange(
-      ConstantRange::intrinsic(II->getIntrinsicID(), OpRanges));
+  return intersect(ValueLatticeElement::getRange(ConstantRange::intrinsic(
+                       II->getIntrinsicID(), OpRanges)),
+                   MetadataVal);
 }
 
 std::optional<ValueLatticeElement>

diff  --git a/llvm/test/Transforms/CorrelatedValuePropagation/range.ll b/llvm/test/Transforms/CorrelatedValuePropagation/range.ll
index 458ecae0cbc3d..26b31ce8ee096 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/range.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/range.ll
@@ -950,8 +950,7 @@ define i1 @supported_intrinsic_range(i16 %x) {
 ; CHECK-LABEL: @supported_intrinsic_range(
 ; CHECK-NEXT:    [[ABS:%.*]] = call i16 @llvm.abs.i16(i16 [[X:%.*]], i1 false), !range [[RNG5]]
 ; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i16 [[ABS]] to i8
-; CHECK-NEXT:    [[RES:%.*]] = icmp ult i8 [[TRUNC]], 8
-; CHECK-NEXT:    ret i1 [[RES]]
+; CHECK-NEXT:    ret i1 true
 ;
   %abs = call i16 @llvm.abs.i16(i16 %x, i1 false), !range !{i16 0, i16 8}
   %trunc = trunc i16 %abs to i8