[PATCH] D117929: [XRay] Add support for RISCV

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added inline comments.


================
Comment at: compiler-rt/lib/xray/xray_trampoline_riscv32.S:54
+	// Handler address will be null if it is not set
+	beq	a2, x0, FunctionEntry_restore
+
----------------
This local symbol doesn't seem useful. We can just use numbers (`1f` and `1:`) or `LOCAL_LABEL(...)`, so that the symbol table will not have the unneeded symbol entries.


================
Comment at: compiler-rt/lib/xray/xray_trampoline_riscv32.S:85
+FunctionEntry_end:
+	ASM_SIZE(__xray_FunctionEntry)
+	.cfi_endproc
----------------
stray `ASM_SIZE`?


================
Comment at: compiler-rt/lib/xray/xray_trampoline_riscv64.S:22
+	ASM_TYPE_FUNCTION(__xray_FunctionEntry)
+	ASM_SYMBOL(__xray_FunctionEntry):
+	.cfi_startproc
----------------
See the aarch64 implementation to use `ASM_SIZE(__xray_FunctionEntry)` to set `.size`


================
Comment at: llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp:185
+    if (F.hasFnAttribute("patchable-function-entry")) {
+      break;
+    }
----------------
omit braces for single-line single statement body.


================
Comment at: llvm/lib/Target/RISCV/RISCVSubtarget.h:164
+  // Add XRay support - needs double precision floats at present and does not
+  // support compressed instructions
+  bool isXRaySupported() const override {
----------------
"does not support compressed instructions" makes this feature infeasible for many systems, I'll say probably almost all systems that may consider XRay. 


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D117929/new/

https://reviews.llvm.org/D117929