Ignore "no-frame-pointer-elim" and "no-frame-pointer-elim-non-leaf" in favor of "frame-pointer"

D56351 (included in LLVM 8.0.0) introduced "frame-pointer".  All tests
which use "no-frame-pointer-elim" or "no-frame-pointer-elim-non-leaf"
have been migrated to use "frame-pointer".

Implement UpgradeFramePointerAttributes to upgrade the two obsoleted
function attributes for bitcode. Their semantics are ignored.

Differential Revision: https://reviews.llvm.org/D71863

3 files changed, 22 insertions, 13 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 3a56c1aa93b..33464412edc 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1661,6 +1661,7 @@ Error BitcodeReader::parseAttributeGroupBlock() {
         }
       }
 
+      UpgradeFramePointerAttributes(B);
       MAttributeGroups[GrpID] = AttributeList::get(Context, Idx, B);
       break;
     }
diff --git a/llvm/lib/CodeGen/TargetOptionsImpl.cpp b/llvm/lib/CodeGen/TargetOptionsImpl.cpp
index 039748d817c..d794a261ecb 100644
--- a/llvm/lib/CodeGen/TargetOptionsImpl.cpp
+++ b/llvm/lib/CodeGen/TargetOptionsImpl.cpp
@@ -28,20 +28,8 @@ bool TargetOptions::DisableFramePointerElim(const MachineFunction &MF) const {
 
   const Function &F = MF.getFunction();
 
-  // TODO: Remove support for old `fp elim` function attributes after fully
-  //       migrate to use "frame-pointer"
-  if (!F.hasFnAttribute("frame-pointer")) {
-    // Check to see if we should eliminate all frame pointers.
-    if (F.getFnAttribute("no-frame-pointer-elim").getValueAsString() == "true")
-      return true;
-
-    // Check to see if we should eliminate non-leaf frame pointers.
-    if (F.hasFnAttribute("no-frame-pointer-elim-non-leaf"))
-      return MF.getFrameInfo().hasCalls();
-
+  if (!F.hasFnAttribute("frame-pointer"))
     return false;
-  }
-
   StringRef FP = F.getFnAttribute("frame-pointer").getValueAsString();
   if (FP == "all")
     return true;
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index d73e511382e..83bf052eb08 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -4177,3 +4177,23 @@ std::string llvm::UpgradeDataLayoutString(StringRef DL, StringRef TT) {
   std::string Res = (Groups[1] + AddrSpaces + Groups[3]).toStringRef(Buf).str();
   return Res;
 }
+
+void llvm::UpgradeFramePointerAttributes(AttrBuilder &B) {
+  StringRef FramePointer;
+  if (B.contains("no-frame-pointer-elim")) {
+    // The value can be "true" or "false".
+    for (const auto &I : B.td_attrs())
+      if (I.first == "no-frame-pointer-elim")
+        FramePointer = I.second == "true" ? "all" : "none";
+    B.removeAttribute("no-frame-pointer-elim");
+  }
+  if (B.contains("no-frame-pointer-elim-non-leaf")) {
+    // The value is ignored. "no-frame-pointer-elim"="true" takes priority.
+    if (FramePointer != "all")
+      FramePointer = "non-leaf";
+    B.removeAttribute("no-frame-pointer-elim-non-leaf");
+  }
+
+  if (!FramePointer.empty())
+    B.addAttribute("frame-pointer", FramePointer);
+}