[AArch64] Inline callee if its target-features are a subset of the caller

Summary:
Similar to X86, it should be safe to inline callees if their target-features
are a subset of the caller. This change matches GCC's inlining behavior
with respect to attributes [1].

[1] https://gcc.gnu.org/onlinedocs/gcc/AArch64-Function-Attributes.html#AArch64-Function-Attributes

Reviewers: kristof.beyls, javed.absar, rengolin, t.p.northover

Reviewed By: t.p.northover

Subscribers: aemerson, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D34698

llvm-svn: 306478

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index a4328682b93..1d0f0b98b76 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -20,6 +20,20 @@ using namespace llvm;
 
 #define DEBUG_TYPE "aarch64tti"
 
+bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
+                                         const Function *Callee) const {
+  const TargetMachine &TM = getTLI()->getTargetMachine();
+
+  const FeatureBitset &CallerBits =
+      TM.getSubtargetImpl(*Caller)->getFeatureBits();
+  const FeatureBitset &CalleeBits =
+      TM.getSubtargetImpl(*Callee)->getFeatureBits();
+
+  // Inline a callee if its target-features are a subset of the callers
+  // target-features.
+  return (CallerBits & CalleeBits) == CalleeBits;
+}
+
 /// \brief Calculate the cost of materializing a 64-bit value. This helper
 /// method might only calculate a fraction of a larger immediate. Therefore it
 /// is valid to return a cost of ZERO.