[ConstantFolding] Merge constant gep inrange attributes (llvm#150546)

When folding a gep+gep into a single gep, intersect their `inrange`
attributes.

Author: pedroclobo

llvm/lib/Analysis/ConstantFolding.cpp

@@ -929,12 +929,11 @@ Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
     if (!AllConstantInt)
       break;
 
-    // TODO: Try to intersect two inrange attributes?
-    if (!InRange) {
-      InRange = GEP->getInRange();
-      if (InRange)
-        // Adjust inrange by offset until now.
-        InRange = InRange->sextOrTrunc(BitWidth).subtract(Offset);
+    // Adjust inrange offset and intersect inrange attributes
+    if (auto GEPRange = GEP->getInRange()) {
+      auto AdjustedGEPRange = GEPRange->sextOrTrunc(BitWidth).subtract(Offset);
+      InRange =
+          InRange ? InRange->intersectWith(AdjustedGEPRange) : AdjustedGEPRange;
     }
 
     Ptr = cast<Constant>(GEP->getOperand(0));

llvm/test/Transforms/InstSimplify/ConstProp/gep.ll

@@ -29,3 +29,31 @@ define ptr @f2() {
 ;
   ret ptr getelementptr (ptr, ptr getelementptr inbounds inrange(0, 8) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 3)
 }
+
+define ptr @f3() {
+; CHECK-LABEL: @f3(
+; CHECK-NEXT:    ret ptr getelementptr inbounds nuw inrange(-8, 0) (i8, ptr @vt, i64 16)
+;
+  ret ptr getelementptr inrange(-16, 8) (ptr, ptr getelementptr inbounds inrange(0, 8) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 1)
+}
+
+define ptr @f4() {
+; CHECK-LABEL: @f4(
+; CHECK-NEXT:    ret ptr getelementptr inbounds nuw inrange(-8, 8) (i8, ptr @vt, i64 16)
+;
+  ret ptr getelementptr inrange(-16, 8) (ptr, ptr getelementptr inbounds inrange(0, 24) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 1)
+}
+
+define ptr @f5() {
+; CHECK-LABEL: @f5(
+; CHECK-NEXT:    ret ptr getelementptr inbounds nuw inrange(0, 0) (i8, ptr @vt, i64 16)
+;
+  ret ptr getelementptr inrange(0, 8) (ptr, ptr getelementptr inbounds inrange(0, 8) ([3 x ptr], ptr @vt, i64 0, i64 0), i64 2)
+}
+
+define ptr @f6() {
+; CHECK-LABEL: @f6(
+; CHECK-NEXT:    ret ptr getelementptr inbounds nuw inrange(-8, 8) (i8, ptr @vt, i64 16)
+;
+  ret ptr getelementptr inrange(-8, 8) (ptr, ptr getelementptr inbounds inrange(-8, 16) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 1)
+}