[XRay][RISCV] RISCV support for XRay (#117368)

Add RISC-V support for XRay. The RV64 implementation has been tested in
both QEMU and in our hardware environment.

Currently this requires D and C extensions, but since both RV64GC and
RVA22/RVA23 are becoming mainstream, I don't think this requirement will
be a big problem.

Based on the previous work by @a-poduval :
https://reviews.llvm.org/D117929

---------

Co-authored-by: Ashwin Poduval <ashwin.poduval@gmail.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/XRayInstrumentation.cpp b/llvm/lib/CodeGen/XRayInstrumentation.cpp
index 8f718d8..8af16fa 100644
--- a/llvm/lib/CodeGen/XRayInstrumentation.cpp
+++ b/llvm/lib/CodeGen/XRayInstrumentation.cpp
@@ -233,10 +233,13 @@ bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) {
     case Triple::ArchType::mips:
     case Triple::ArchType::mipsel:
     case Triple::ArchType::mips64:
-    case Triple::ArchType::mips64el: {
+    case Triple::ArchType::mips64el:
+    case Triple::ArchType::riscv32:
+    case Triple::ArchType::riscv64: {
       // For the architectures which don't have a single return instruction
       InstrumentationOptions op;
-      op.HandleTailcall = false;
+      // RISC-V supports patching tail calls.
+      op.HandleTailcall = MF.getTarget().getTargetTriple().isRISCV();
       op.HandleAllReturns = true;
       prependRetWithPatchableExit(MF, TII, op);
       break;