[llvm] [EntryExitInstrumenter][AArch64][RISCV][LoongArch] Pass `__builtin_return_address(0)` into `_mcount` (PR #121107)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Yingwei Zheng (dtcxzyw)

<details>
<summary>Changes</summary>

On RISC-V, AArch64, and LoongArch, the `_mcount` function takes `__builtin_return_address(0)` as an argument since `__builtin_return_address(1)` is not available on these platforms. This patch fixes the argument passing to match the behavior of glibc/gcc.

Closes https://github.com/llvm/llvm-project/issues/121103.


---
Full diff: https://github.com/llvm/llvm-project/pull/121107.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp (+15) 
- (added) llvm/test/Transforms/EntryExitInstrumenter/mcount-with-frompc.ll (+24) 


``````````diff
diff --git a/llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp b/llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp
index 47bb31905d1ac8..5b33edd51cffa6 100644
--- a/llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp
+++ b/llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp
@@ -48,6 +48,21 @@ static void insertCall(Function &CurFn, StringRef Func,
                                                   /*isVarArg=*/false)),
           {GV}, "", InsertionPt);
       Call->setDebugLoc(DL);
+    } else if (TargetTriple.isRISCV() || TargetTriple.isAArch64() ||
+               TargetTriple.isLoongArch()) {
+      // On RISC-V, AArch64, and LoongArch, the `_mcount` function takes
+      // `__builtin_return_address(0)` as an argument since
+      // `__builtin_return_address(1)` is not available on these platforms.
+      Instruction *RetAddr = CallInst::Create(
+          Intrinsic::getOrInsertDeclaration(&M, Intrinsic::returnaddress),
+          ConstantInt::get(Type::getInt32Ty(C), 0), "", InsertionPt);
+      RetAddr->setDebugLoc(DL);
+
+      FunctionCallee Fn = M.getOrInsertFunction(
+          Func, FunctionType::get(Type::getVoidTy(C), PointerType::getUnqual(C),
+                                  false));
+      CallInst *Call = CallInst::Create(Fn, RetAddr, "", InsertionPt);
+      Call->setDebugLoc(DL);
     } else {
       FunctionCallee Fn = M.getOrInsertFunction(Func, Type::getVoidTy(C));
       CallInst *Call = CallInst::Create(Fn, "", InsertionPt);
diff --git a/llvm/test/Transforms/EntryExitInstrumenter/mcount-with-frompc.ll b/llvm/test/Transforms/EntryExitInstrumenter/mcount-with-frompc.ll
new file mode 100644
index 00000000000000..5123b2270eafa5
--- /dev/null
+++ b/llvm/test/Transforms/EntryExitInstrumenter/mcount-with-frompc.ll
@@ -0,0 +1,24 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -mtriple=riscv64 -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,RISCV64
+; RUN: opt -mtriple=riscv32 -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,RISCV32
+; RUN: opt -mtriple=loongarch64 -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,LOONGARCH64
+; RUN: opt -mtriple=loongarch32 -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,LOONGARCH32
+; RUN: opt -mtriple=aarch64 -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,AARCH64
+; RUN: opt -mtriple=aarch64_be -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,AARCH64_BE
+; RUN: opt -mtriple=aarch64_32 -passes=ee-instrument -S < %s | FileCheck %s --check-prefixes=CHECK,AARCH64_32
+
+define void @f1() "instrument-function-entry-inlined"="_mcount" {
+; CHECK-LABEL: define void @f1(
+; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:    ret void
+;
+  ret void
+}
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; AARCH64: {{.*}}
+; AARCH64_32: {{.*}}
+; AARCH64_BE: {{.*}}
+; LOONGARCH32: {{.*}}
+; LOONGARCH64: {{.*}}
+; RISCV32: {{.*}}
+; RISCV64: {{.*}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/121107