[llvm-branch-commits] [llvm] a9f083d - [SCEV] Fix potentially empty set for unsigned ranges

[Tobias Hieta via llvm-branch-commits]

Author: Tejas Joshi
Date: 2023-09-11T08:56:18+02:00
New Revision: a9f083d30500565091626213f9775f89b1376335

URL: https://github.com/llvm/llvm-project/commit/a9f083d30500565091626213f9775f89b1376335
DIFF: https://github.com/llvm/llvm-project/commit/a9f083d30500565091626213f9775f89b1376335.diff

LOG: [SCEV] Fix potentially empty set for unsigned ranges

The following commit enabled the analysis of ranges for heap allocations:
22ca38da25e19a7c5fcfeb3f22159aba92ec381e

The range turns out to be empty in cases such as the one in test (which
is [1,1)), leading to an assertion failure. This patch fixes for the
same case.

Fixes https://github.com/llvm/llvm-project/issues/63856

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D159160

(cherry picked from commit 0609b65aaf03b083d282a4ffe8bf660351dac461)

Added: 
    

Modified: 
    llvm/lib/Analysis/ScalarEvolution.cpp
    llvm/test/Analysis/ScalarEvolution/malloc.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 111d4d30aab9611..39ab48b4a48e176 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -6833,7 +6833,7 @@ const ConstantRange &ScalarEvolution::getRangeRef(
         if (llvm::isKnownNonZero(V, DL))
           MinVal = Align;
         ConservativeResult = ConservativeResult.intersectWith(
-            {MinVal, MaxVal + 1}, RangeType);
+            ConstantRange::getNonEmpty(MinVal, MaxVal + 1), RangeType);
       }
     }
 

diff  --git a/llvm/test/Analysis/ScalarEvolution/malloc.ll b/llvm/test/Analysis/ScalarEvolution/malloc.ll
index 80d1d65c7981de9..578220cf5c37cc5 100644
--- a/llvm/test/Analysis/ScalarEvolution/malloc.ll
+++ b/llvm/test/Analysis/ScalarEvolution/malloc.ll
@@ -23,4 +23,15 @@ define ptr @f2() {
   ret ptr %alloc
 }
 
+define ptr @undefined_max() {
+; CHECK-LABEL: 'undefined_max'
+; CHECK-NEXT:  Classifying expressions for: @undefined_max
+; CHECK-NEXT:    %alloc = call nonnull ptr @malloc(i64 -1)
+; CHECK-NEXT:    -->  %alloc U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @undefined_max
+;
+  %alloc = call nonnull ptr @malloc(i64 -1)
+  ret ptr %alloc
+}
+
 declare noalias noundef ptr @malloc(i64 noundef) allockind("alloc,uninitialized") allocsize(0)