[VFABI] Add LLVM internal mangling for vector functions.

Summary:
This patch adds a custom ISA for vector functions for internal use
in LLVM. The <isa> token is set to "_LLVM_", and it is not attached
to any specific instruction Vector ISA, or Vector Function ABI.

The ISA is used as a token for handling Vector Function ABI-style
vectorization for those vector functions that are not directly
associated to any existing Vector Function ABI (for example, some of
the vector functions exposed by TargetLibraryInfo). The demangling
function for this ISA in a Vector Function ABI context is set to be
the same as the common one shared between X86 and AArch64.

Reviewers: jdoerfert, sdesmalen, simoll

Subscribers: kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70089

1 files changed, 20 insertions, 9 deletions

diff --git a/llvm/lib/Analysis/VFABIDemangling.cpp b/llvm/lib/Analysis/VFABIDemangling.cpp
index 152f7ae4667..067283d38b6 100644
--- a/llvm/lib/Analysis/VFABIDemangling.cpp
+++ b/llvm/lib/Analysis/VFABIDemangling.cpp
@@ -28,15 +28,20 @@ ParseRet tryParseISA(StringRef &MangledName, VFISAKind &ISA) {
   if (MangledName.empty())
     return ParseRet::Error;
 
-  ISA = StringSwitch<VFISAKind>(MangledName.take_front(1))
-            .Case("n", VFISAKind::AdvancedSIMD)
-            .Case("s", VFISAKind::SVE)
-            .Case("b", VFISAKind::SSE)
-            .Case("c", VFISAKind::AVX)
-            .Case("d", VFISAKind::AVX2)
-            .Case("e", VFISAKind::AVX512)
-            .Default(VFISAKind::Unknown);
-  MangledName = MangledName.drop_front(1);
+  if (MangledName.startswith(VFABI::_LLVM_)) {
+    MangledName = MangledName.drop_front(strlen(VFABI::_LLVM_));
+    ISA = VFISAKind::LLVM;
+  } else {
+    ISA = StringSwitch<VFISAKind>(MangledName.take_front(1))
+              .Case("n", VFISAKind::AdvancedSIMD)
+              .Case("s", VFISAKind::SVE)
+              .Case("b", VFISAKind::SSE)
+              .Case("c", VFISAKind::AVX)
+              .Case("d", VFISAKind::AVX2)
+              .Case("e", VFISAKind::AVX512)
+              .Default(VFISAKind::Unknown);
+    MangledName = MangledName.drop_front(1);
+  }
 
   return ParseRet::OK;
 }
@@ -287,6 +292,7 @@ ParseRet tryParseAlign(StringRef &ParseString, Align &Alignment) {
 // Format of the ABI name:
 // _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)]
 Optional<VFInfo> VFABI::tryDemangleForVFABI(StringRef MangledName) {
+  const StringRef OriginalName = MangledName;
   // Assume there is no custom name <redirection>, and therefore the
   // vector name consists of
   // _ZGV<isa><mask><vlen><parameters>_<scalarname>.
@@ -370,6 +376,11 @@ Optional<VFInfo> VFABI::tryDemangleForVFABI(StringRef MangledName) {
       return None;
   }
 
+  // LLVM internal mapping via the TargetLibraryInfo (TLI) must be
+  // redirected to an existing name.
+  if (ISA == VFISAKind::LLVM && VectorName == OriginalName)
+    return None;
+
   // When <mask> is "M", we need to add a parameter that is used as
   // global predicate for the function.
   if (IsMasked) {