[llvm][AArch64] Do not inline a function with different signing scheme. (#80642)

[DanielKristofKiss]

f the signing scheme is different that maybe the functions assumes different behaviours and dangerous to inline them without analysing them. This should be a rare case.

[llvmbot]

@llvm/pr-subscribers-llvm-ir

@llvm/pr-subscribers-llvm-transforms

Author: Dani (DanielKristofKiss)

Changes

f the signing scheme is different that maybe the functions assumes different behaviours and dangerous to inline them without analysing them. This should be a rare case.

---

Full diff: https://github.com/llvm/llvm-project/pull/82743.diff

4 Files Affected:

• (modified) llvm/include/llvm/IR/Attributes.td (+21-7)
• (modified) llvm/lib/IR/Attributes.cpp (+5)
• (added) llvm/test/Transforms/Inline/inline-sign-return-address.ll (+104)
• (modified) llvm/utils/TableGen/Attributes.cpp (+5-1)

diff --git a/llvm/include/llvm/IR/Attributes.td b/llvm/include/llvm/IR/Attributes.td
index 864f87f3383891..d22eb76d2292d5 100644
--- a/llvm/include/llvm/IR/Attributes.td
+++ b/llvm/include/llvm/IR/Attributes.td
@@ -339,14 +339,26 @@ def UseSampleProfile : StrBoolAttr<"use-sample-profile">;
 def DenormalFPMath : ComplexStrAttr<"denormal-fp-math", [FnAttr]>;
 def DenormalFPMathF32 : ComplexStrAttr<"denormal-fp-math-f32", [FnAttr]>;
 
+// Attribute compatiblity rules are generated to check the attribute of the
+// caller and callee and decide whether inlining should be allowed. CompatRule
+// and child classes are used for the rule generation. CompatRule takes only a
+// compare function which could be templated with the attribute type.
+// CompatRuleStrAttr takes the compare function and the string attribute for
+// checking compatibility for inline substitution.
 class CompatRule<string F> {
-  // The name of the function called to check the attribute of the caller and
-  // callee and decide whether inlining should be allowed. The function's
-  // signature must match "bool(const Function&, const Function &)", where the
-  // first parameter is the reference to the caller and the second parameter is
-  // the reference to the callee. It must return false if the attributes of the
-  // caller and callee are incompatible, and true otherwise.
+  // The function's signature must match "bool(const Function&, const
+  // Function&)", where the first parameter is the reference to the caller and
+  // the second parameter is the reference to the callee. It must return false
+  // if the attributes of the caller and callee are incompatible, and true
+  // otherwise.
   string CompatFunc = F;
+  string AttrName = "";
+}
+
+class CompatRuleStrAttr<string F, string Attr> : CompatRule<F> {
+  // The checker function is extended with an third argument as the function
+  // attribute string "bool(const Function&, const Function&, const StringRef&)".
+  string AttrName = Attr;
 }
 
 def : CompatRule<"isEqual<SanitizeAddressAttr>">;
@@ -359,7 +371,9 @@ def : CompatRule<"isEqual<ShadowCallStackAttr>">;
 def : CompatRule<"isEqual<UseSampleProfileAttr>">;
 def : CompatRule<"isEqual<NoProfileAttr>">;
 def : CompatRule<"checkDenormMode">;
-
+def : CompatRuleStrAttr<"isEqual", "sign-return-address">;
+def : CompatRuleStrAttr<"isEqual", "sign-return-address-key">;
+def : CompatRuleStrAttr<"isEqual", "branch-protection-pauth-lr">;
 
 class MergeRule<string F> {
   // The name of the function called to merge the attributes of the caller and
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index fd5160209506f2..19076771ff2eaf 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -2045,6 +2045,11 @@ static bool isEqual(const Function &Caller, const Function &Callee) {
          Callee.getFnAttribute(AttrClass::getKind());
 }
 
+static bool isEqual(const Function &Caller, const Function &Callee,
+                    const StringRef &AttrName) {
+  return Caller.getFnAttribute(AttrName) == Callee.getFnAttribute(AttrName);
+}
+
 /// Compute the logical AND of the attributes of the caller and the
 /// callee.
 ///
diff --git a/llvm/test/Transforms/Inline/inline-sign-return-address.ll b/llvm/test/Transforms/Inline/inline-sign-return-address.ll
new file mode 100644
index 00000000000000..c4d85fa671a4f6
--- /dev/null
+++ b/llvm/test/Transforms/Inline/inline-sign-return-address.ll
@@ -0,0 +1,104 @@
+; Check the inliner doesn't inline a function with different sign return address schemes.
+; RUN: opt < %s -passes=inline -S | FileCheck %s
+
+define internal void @foo_all() #0 {
+  ret void
+}
+
+define internal void @foo_nonleaf() #1 {
+  ret void
+}
+
+define internal void @foo_none() #2 {
+  ret void
+}
+
+define internal void @foo_lr() #3 {
+  ret void
+}
+
+define internal void @foo_bkey() #4 {
+  ret void
+}
+
+define dso_local void @bar_all() #0 {
+; CHECK-LABEL: bar_all
+; CHECK-NOT:     call void @foo_all()
+; CHECK-NEXT:    call void @foo_nonleaf()
+; CHECK-NEXT:    call void @foo_none()
+; CHECK-NEXT:    call void @foo_lr()
+; CHECK-NEXT:    call void @foo_bkey()
+  call void @foo_all()
+  call void @foo_nonleaf()
+  call void @foo_none()
+  call void @foo_lr()
+  call void @foo_bkey()
+  ret void
+}
+
+define dso_local void @bar_nonleaf() #1 {
+; CHECK-LABEL: bar_nonleaf
+; CHECK-NEXT:    call void @foo_all()
+; CHECK-NOT:     call void @foo_nonleaf()
+; CHECK-NEXT:    call void @foo_none()
+; CHECK-NEXT:    call void @foo_lr()
+; CHECK-NEXT:    call void @foo_bkey()
+  call void @foo_all()
+  call void @foo_nonleaf()
+  call void @foo_none()
+  call void @foo_lr()
+  call void @foo_bkey()
+  ret void
+}
+
+define dso_local void @bar_none() #2 {
+; CHECK-LABEL: bar_none
+; CHECK-NEXT:    call void @foo_all()
+; CHECK-NEXT:    call void @foo_nonleaf()
+; CHECK-NOT:     call void @foo_none()
+; CHECK-NEXT:    call void @foo_lr()
+; CHECK-NEXT:    call void @foo_bkey()
+  call void @foo_all()
+  call void @foo_nonleaf()
+  call void @foo_none()
+  call void @foo_lr()
+  call void @foo_bkey()
+  ret void
+}
+
+define dso_local void @bar_lr() #3 {
+; CHECK-LABEL: bar_lr
+; CHECK-NEXT:    call void @foo_all()
+; CHECK-NEXT:    call void @foo_nonleaf()
+; CHECK-NEXT:    call void @foo_none()
+; CHECK-NOT:     call void @foo_lr()
+; CHECK-NEXT:    call void @foo_bkey()
+  call void @foo_all()
+  call void @foo_nonleaf()
+  call void @foo_none()
+  call void @foo_lr()
+  call void @foo_bkey()
+  ret void
+}
+
+define dso_local void @bar_bkey() #4 {
+; CHECK-LABEL: bar_bkey
+; CHECK-NEXT:    call void @foo_all()
+; CHECK-NEXT:    call void @foo_nonleaf()
+; CHECK-NEXT:    call void @foo_none()
+; CHECK-NEXT:    call void @foo_lr()
+; CHECK-NOT:     call void @foo_bkey()
+  call void @foo_all()
+  call void @foo_nonleaf()
+  call void @foo_none()
+  call void @foo_lr()
+  call void @foo_bkey()
+  ret void
+}
+
+
+attributes #0 = { "branch-protection-pauth-lr"="false" "sign-return-address"="all" }
+attributes #1 = { "branch-protection-pauth-lr"="false" "sign-return-address"="non-leaf" }
+attributes #2 = { "branch-protection-pauth-lr"="false" "sign-return-address"="none" }
+attributes #3 = { "branch-protection-pauth-lr"="true" "sign-return-address"="non-leaf" }
+attributes #4 = { "branch-protection-pauth-lr"="true" "sign-return-address"="non-leaf" "sign-return-address-key"="b_key" }
\ No newline at end of file
diff --git a/llvm/utils/TableGen/Attributes.cpp b/llvm/utils/TableGen/Attributes.cpp
index 474042a3e9a331..db3c4decccb4cf 100644
--- a/llvm/utils/TableGen/Attributes.cpp
+++ b/llvm/utils/TableGen/Attributes.cpp
@@ -87,7 +87,11 @@ void Attributes::emitFnAttrCompatCheck(raw_ostream &OS, bool IsStringAttr) {
 
   for (auto *Rule : CompatRules) {
     StringRef FuncName = Rule->getValueAsString("CompatFunc");
-    OS << "  Ret &= " << FuncName << "(Caller, Callee);\n";
+    OS << "  Ret &= " << FuncName << "(Caller, Callee";
+    StringRef AttrName = Rule->getValueAsString("AttrName");
+    if (!AttrName.empty())
+      OS << ", \"" << AttrName << "\"";
+    OS << ");\n";
   }
 
   OS << "\n";

[tstellar]

@nickdesaulniers What do you think about backporting this?

[nickdesaulniers]

LGTM

[nickdesaulniers]

(also, I think you can use /backport <sha> comment in any issue and llvmbot will generate these PRs for you.)