[clang] [llvm] [Inliner] Propagate more attributes to params when inlining (PR #91101)

[Nikita Popov via cfe-commits]

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@@ -1381,21 +1405,58 @@ static void AddParamAndFnBasicAttributes(const CallBase &CB,
       AttributeList AL = NewInnerCB->getAttributes();
       for (unsigned I = 0, E = InnerCB->arg_size(); I < E; ++I) {
         // Check if the underlying value for the parameter is an argument.
-        const Value *UnderlyingV =
-            getUnderlyingObject(InnerCB->getArgOperand(I));
-        const Argument *Arg = dyn_cast<Argument>(UnderlyingV);
-        if (!Arg)
-          continue;
+        const Argument *Arg = dyn_cast<Argument>(InnerCB->getArgOperand(I));
+        unsigned ArgNo;
+        if (Arg) {
+          ArgNo = Arg->getArgNo();
+          // For dereferenceable, dereferenceable_or_null, align, etc...
+          // we don't want to propagate if the existing param has the same
+          // attribute with "better" constraints. So, only remove from the
+          // existing AL if the region of the existing param is smaller than
+          // what we can propagate. AttributeList's merge API honours the
+          // already existing attribute value so we choose the "better"
+          // attribute by removing if the existing one is worse.
+          if (AL.getParamDereferenceableBytes(I) <
+              ValidExactParamAttrs[ArgNo].getDereferenceableBytes())
+            AL =
+                AL.removeParamAttribute(Context, I, Attribute::Dereferenceable);
+          if (AL.getParamDereferenceableOrNullBytes(I) <
+              ValidExactParamAttrs[ArgNo].getDereferenceableOrNullBytes())
+            AL =
+                AL.removeParamAttribute(Context, I, Attribute::Dereferenceable);
+          if (AL.getParamAlignment(I).valueOrOne() <
+              ValidExactParamAttrs[ArgNo].getAlignment().valueOrOne())
+            AL = AL.removeParamAttribute(Context, I, Attribute::Alignment);
+
+          auto ExistingRange = AL.getParamRange(I);
+          AL = AL.addParamAttributes(Context, I, ValidExactParamAttrs[ArgNo]);
+
+          // For range we use the intersection.
+          if (ExistingRange.has_value()) {
+            if (auto NewRange = ValidExactParamAttrs[ArgNo].getRange()) {
+              auto CombinedRange = ExistingRange->intersectWith(*NewRange);
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nikic wrote:

auto -> ConstantRange

https://github.com/llvm/llvm-project/pull/91101