[PATCH] D49162: [Inliner] Teach inliner to merge 'min-legal-vector-width' function attribute

[Craig Topper via Phabricator via llvm-commits]

craig.topper updated this revision to Diff 157074.
craig.topper added a comment.

Improve comment.

As I mentioned on IRC always_inline doesn't go through inline cost analysis including attribute compatibility checking. So this patch is the minimum necessary to make intrinsics propagate their vector width to the function they get inlined into.


https://reviews.llvm.org/D49162

Files:
  include/llvm/IR/Attributes.td
  lib/IR/Attributes.cpp


Index: lib/IR/Attributes.cpp
===================================================================
--- lib/IR/Attributes.cpp
+++ lib/IR/Attributes.cpp
@@ -1682,6 +1682,33 @@
   }
 }
 
+/// If the inlined function defines a min legal vector width, then ensure
+/// the calling function has the same or larger min legal vector width. This
+/// function is called after the inlining decision has been made so we have to
+/// merge the attribute this way. Heuristics that would use
+/// min-legal-vector-width to determine inline compatibility would need to be
+/// handled as part of inline cost analysis.
+static void
+adjustMinLegalVectorWidth(Function &Caller, const Function &Callee) {
+  if (Callee.hasFnAttribute("min-legal-vector-width")) {
+    uint64_t CalleeVectorWidth;
+    Callee.getFnAttribute("min-legal-vector-width")
+          .getValueAsString()
+          .getAsInteger(0, CalleeVectorWidth);
+    if (Caller.hasFnAttribute("min-legal-vector-width")) {
+      uint64_t CallerVectorWidth;
+      Caller.getFnAttribute("min-legal-vector-width")
+            .getValueAsString()
+            .getAsInteger(0, CallerVectorWidth);
+      if (CallerVectorWidth < CalleeVectorWidth) {
+        Caller.addFnAttr(Callee.getFnAttribute("min-legal-vector-width"));
+      }
+    } else {
+      Caller.addFnAttr(Callee.getFnAttribute("min-legal-vector-width"));
+    }
+  }
+}
+
 #define GET_ATTR_COMPAT_FUNC
 #include "AttributesCompatFunc.inc"
 
Index: include/llvm/IR/Attributes.td
===================================================================
--- include/llvm/IR/Attributes.td
+++ include/llvm/IR/Attributes.td
@@ -235,3 +235,4 @@
 def : MergeRule<"adjustCallerSSPLevel">;
 def : MergeRule<"adjustCallerStackProbes">;
 def : MergeRule<"adjustCallerStackProbeSize">;
+def : MergeRule<"adjustMinLegalVectorWidth">;


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