[llvm] 6cb087a - [XRay] Fix tail call sleds for AArch64 (#141403)

[via llvm-commits]

Author: Sebastian Kreutzer
Date: 2025-05-29T21:54:15-07:00
New Revision: 6cb087a7256c04cc8fc783159ff6e4de69908632

URL: https://github.com/llvm/llvm-project/commit/6cb087a7256c04cc8fc783159ff6e4de69908632
DIFF: https://github.com/llvm/llvm-project/commit/6cb087a7256c04cc8fc783159ff6e4de69908632.diff

LOG: [XRay] Fix tail call sleds for AArch64 (#141403)

This addresses issue #141051.
XRay uses a special event kind for tail calls on some architectures.
This feature is implemented on AArch64, but wasn't fully activated.
Tests in `llvm/test/CodeGen/AArch64/xray-tail-call-sled.ll` were
incomplete and did not check for the emitted sled type.
This patch correctly enables emission of tail call sleds on AArch64 and
fixes the tests to check the sled kind.

Added: 
    

Modified: 
    llvm/lib/CodeGen/XRayInstrumentation.cpp
    llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
    llvm/test/CodeGen/AArch64/xray-tail-call-sled.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/XRayInstrumentation.cpp b/llvm/lib/CodeGen/XRayInstrumentation.cpp
index dbdb81d1e6b33..d2f40581ecebf 100644
--- a/llvm/lib/CodeGen/XRayInstrumentation.cpp
+++ b/llvm/lib/CodeGen/XRayInstrumentation.cpp
@@ -296,8 +296,9 @@ bool XRayInstrumentation::run(MachineFunction &MF) {
     case Triple::ArchType::riscv64: {
       // For the architectures which don't have a single return instruction
       InstrumentationOptions op;
-      // RISC-V supports patching tail calls.
-      op.HandleTailcall = MF.getTarget().getTargetTriple().isRISCV();
+      // AArch64 and RISC-V support patching tail calls.
+      op.HandleTailcall = MF.getTarget().getTargetTriple().isAArch64() ||
+                          MF.getTarget().getTargetTriple().isRISCV();
       op.HandleAllReturns = true;
       prependRetWithPatchableExit(MF, TII, op);
       break;

diff  --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index d6225bca233b6..d1e0d37e33e4e 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -162,6 +162,7 @@ unsigned AArch64InstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
         F.getFnAttributeAsParsedInteger("patchable-function-entry", 9) * 4;
     break;
   case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
+  case TargetOpcode::PATCHABLE_TAIL_CALL:
   case TargetOpcode::PATCHABLE_TYPED_EVENT_CALL:
     // An XRay sled can be 4 bytes of alignment plus a 32-byte block.
     NumBytes = 36;

diff  --git a/llvm/test/CodeGen/AArch64/xray-tail-call-sled.ll b/llvm/test/CodeGen/AArch64/xray-tail-call-sled.ll
index 484dca11104ad..a62257e5c9b40 100644
--- a/llvm/test/CodeGen/AArch64/xray-tail-call-sled.ll
+++ b/llvm/test/CodeGen/AArch64/xray-tail-call-sled.ll
@@ -21,8 +21,12 @@ define i32 @callee() nounwind noinline uwtable "function-instrument"="xray-alway
 ; CHECK-LINUX-LABEL: .Lxray_sleds_start0:
 ; CHECK-LINUX-NEXT:  [[TMP:.Ltmp[0-9]+]]:
 ; CHECK-LINUX:         .xword .Lxray_sled_0-[[TMP]]
+; CHECK-LINUX:         .xword
+; CHECK-LINUX-NEXT:    .byte   0x00
 ; CHECK-LINUX:       [[TMP:.Ltmp[0-9]+]]:
 ; CHECK-LINUX-NEXT:    .xword .Lxray_sled_1-[[TMP]]
+; CHECK-LINUX:         .xword
+; CHECK-LINUX-NEXT:    .byte   0x01
 ; CHECK-LINUX-LABEL: Lxray_sleds_end0:
 ; CHECK-LINUX-LABEL: .section xray_fn_idx,"ao", at progbits,callee{{$}}
 ; CHECK-LINUX:         .xword .Lxray_sleds_start0
@@ -32,8 +36,12 @@ define i32 @callee() nounwind noinline uwtable "function-instrument"="xray-alway
 ; CHECK-MACOS-LABEL: lxray_sleds_start0:
 ; CHECK-MACOS-NEXT:  [[TMP:Ltmp[0-9]+]]:
 ; CHECK-MACOS:         .quad Lxray_sled_0-[[TMP]]
+; CHECK-MACOS-NEXT:    .quad
+; CHECK-MACOS-NEXT:    .byte   0x00
 ; CHECK-MACOS:       [[TMP:Ltmp[0-9]+]]:
 ; CHECK-MACOS-NEXT:    .quad Lxray_sled_1-[[TMP]]
+; CHECK-MACOS-NEXT:    .quad
+; CHECK-MACOS-NEXT:    .byte   0x01
 ; CHECK-MACOS-LABEL: Lxray_sleds_end0:
 ; CHECK-MACOS-LABEL: .section __DATA,xray_fn_idx,regular,live_support{{$}}
 ; CHECK-MACOS:       [[IDX:lxray_fn_idx[0-9]+]]:
@@ -60,7 +68,11 @@ define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-alway
 ; CHECK-LINUX-LABEL: .section xray_instr_map,"ao", at progbits,caller{{$}}
 ; CHECK-LINUX-LABEL: Lxray_sleds_start1:
 ; CHECK-LINUX:         .xword .Lxray_sled_2
+; CHECK-LINUX-NEXT:    .xword
+; CHECK-LINUX-NEXT:    .byte   0x00
 ; CHECK-LINUX:         .xword .Lxray_sled_3
+; CHECK-LINUX-NEXT:    .xword
+; CHECK-LINUX-NEXT:    .byte   0x02
 ; CHECK-LINUX-LABEL: Lxray_sleds_end1:
 ; CHECK-LINUX-LABEL: .section xray_fn_idx,"ao", at progbits,caller{{$}}
 ; CHECK-LINUX:       [[IDX:\.Lxray_fn_idx[0-9]+]]:
@@ -70,7 +82,11 @@ define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-alway
 ; CHECK-MACOS-LABEL: .section __DATA,xray_instr_map,regular,live_support{{$}}
 ; CHECK-MACOS-LABEL: lxray_sleds_start1:
 ; CHECK-MACOS:         .quad Lxray_sled_2
+; CHECK-MACOS-NEXT:    .quad
+; CHECK-MACOS-NEXT:    .byte   0x00
 ; CHECK-MACOS:         .quad Lxray_sled_3
+; CHECK-MACOS-NEXT:    .quad
+; CHECK-MACOS-NEXT:    .byte   0x02
 ; CHECK-MACOS-LABEL: Lxray_sleds_end1:
 ; CHECK-MACOS-LABEL: .section __DATA,xray_fn_idx,regular,live_support{{$}}
 ; CHECK-MACOS:       [[IDX:lxray_fn_idx[0-9]+]]: