[LoongArch] Report correct instruction size for PATCHABLE_*

[nikic]

This is either the number of nops provided by patchable-function-entry or the size of the xray sled.

See

llvm-project/llvm/lib/Target/LoongArch/LoongArchAsmPrinter.cpp

Line 214 in 7d39664

void LoongArchAsmPrinter::LowerPATCHABLE_FUNCTION_ENTER(

for the corresponding lowering code.

This came up while working on #187703.

[llvmbot]

@llvm/pr-subscribers-backend-loongarch

Author: Nikita Popov (nikic)

Changes

This is either the number of nops provided by patchable-function-entry or the size of the xray sled.

See

llvm-project/llvm/lib/Target/LoongArch/LoongArchAsmPrinter.cpp

Line 214 in 7d39664

void LoongArchAsmPrinter::LowerPATCHABLE_FUNCTION_ENTER(

for the corresponding lowering code.

This came up while working on #187703.

---

Full diff: https://github.com/llvm/llvm-project/pull/188228.diff

1 Files Affected:

• (modified) llvm/lib/Target/LoongArch/LoongArchInstrInfo.cpp (+17)

diff --git a/llvm/lib/Target/LoongArch/LoongArchInstrInfo.cpp b/llvm/lib/Target/LoongArch/LoongArchInstrInfo.cpp
index 2b163d2d62d3a..4b5ce311f7d52 100644
--- a/llvm/lib/Target/LoongArch/LoongArchInstrInfo.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchInstrInfo.cpp
@@ -263,6 +263,23 @@ unsigned LoongArchInstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
     if (NumBytes == 0)
       NumBytes = 4;
     break;
+  case TargetOpcode::PATCHABLE_FUNCTION_ENTER: {
+    const MachineFunction *MF = MI.getParent()->getParent();
+    const Function &F = MF->getFunction();
+    if (F.hasFnAttribute("patchable-function-entry")) {
+      unsigned Num;
+      if (F.getFnAttribute("patchable-function-entry")
+              .getValueAsString()
+              .getAsInteger(10, Num))
+        return 0;
+      return Num * 4;
+    }
+    [[fallthrough]];
+  }
+  case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
+  case TargetOpcode::PATCHABLE_TAIL_CALL:
+    // Size of xray sled (branch + 11 nops).
+    return 12 * 4;
   }
   return NumBytes;
 }

[heiher]

LGTM. It matches the lowering of these patchable nodes. Thanks!