[C API] Add accessors for function prefix and prologue data (#82193)

A test is added to echo.ll, and the echo.cpp part of llvm-c-test is
updated to clone a function's prefix and prologue.

Author: Benjins

llvm/docs/ReleaseNotes.rst

@@ -131,6 +131,18 @@ Changes to the C API
 * Added ``LLVMConstStringInContext2`` function, which better matches the C++
   API by using ``size_t`` for string length. Deprecated ``LLVMConstStringInContext``. 
 
+* Added the following functions for accessing a function's prefix data:
+
+  * ``LLVMHasPrefixData``
+  * ``LLVMGetPrefixData``
+  * ``LLVMSetPrefixData``
+
+* Added the following functions for accessing a function's prologue data:
+
+  * ``LLVMHasPrologueData``
+  * ``LLVMGetPrologueData``
+  * ``LLVMSetPrologueData``
+
 Changes to the CodeGen infrastructure
 -------------------------------------
 

llvm/include/llvm-c/Core.h

@@ -2748,6 +2748,44 @@ const char *LLVMGetGC(LLVMValueRef Fn);
  */
 void LLVMSetGC(LLVMValueRef Fn, const char *Name);
 
+/**
+ * Gets the prefix data associated with a function. Only valid on functions, and
+ * only if LLVMHasPrefixData returns true.
+ * See https://llvm.org/docs/LangRef.html#prefix-data
+ */
+LLVMValueRef LLVMGetPrefixData(LLVMValueRef Fn);
+
+/**
+ * Check if a given function has prefix data. Only valid on functions.
+ * See https://llvm.org/docs/LangRef.html#prefix-data
+ */
+LLVMBool LLVMHasPrefixData(LLVMValueRef Fn);
+
+/**
+ * Sets the prefix data for the function. Only valid on functions.
+ * See https://llvm.org/docs/LangRef.html#prefix-data
+ */
+void LLVMSetPrefixData(LLVMValueRef Fn, LLVMValueRef prefixData);
+
+/**
+ * Gets the prologue data associated with a function. Only valid on functions,
+ * and only if LLVMHasPrologueData returns true.
+ * See https://llvm.org/docs/LangRef.html#prologue-data
+ */
+LLVMValueRef LLVMGetPrologueData(LLVMValueRef Fn);
+
+/**
+ * Check if a given function has prologue data. Only valid on functions.
+ * See https://llvm.org/docs/LangRef.html#prologue-data
+ */
+LLVMBool LLVMHasPrologueData(LLVMValueRef Fn);
+
+/**
+ * Sets the prologue data for the function. Only valid on functions.
+ * See https://llvm.org/docs/LangRef.html#prologue-data
+ */
+void LLVMSetPrologueData(LLVMValueRef Fn, LLVMValueRef prologueData);
+
 /**
  * Add an attribute to a function.
  *

llvm/lib/IR/Core.cpp

@@ -2422,6 +2422,38 @@ void LLVMSetGC(LLVMValueRef Fn, const char *GC) {
     F->clearGC();
 }
 
+LLVMValueRef LLVMGetPrefixData(LLVMValueRef Fn) {
+  Function *F = unwrap<Function>(Fn);
+  return wrap(F->getPrefixData());
+}
+
+LLVMBool LLVMHasPrefixData(LLVMValueRef Fn) {
+  Function *F = unwrap<Function>(Fn);
+  return F->hasPrefixData();
+}
+
+void LLVMSetPrefixData(LLVMValueRef Fn, LLVMValueRef prefixData) {
+  Function *F = unwrap<Function>(Fn);
+  Constant *prefix = unwrap<Constant>(prefixData);
+  F->setPrefixData(prefix);
+}
+
+LLVMValueRef LLVMGetPrologueData(LLVMValueRef Fn) {
+  Function *F = unwrap<Function>(Fn);
+  return wrap(F->getPrologueData());
+}
+
+LLVMBool LLVMHasPrologueData(LLVMValueRef Fn) {
+  Function *F = unwrap<Function>(Fn);
+  return F->hasPrologueData();
+}
+
+void LLVMSetPrologueData(LLVMValueRef Fn, LLVMValueRef prologueData) {
+  Function *F = unwrap<Function>(Fn);
+  Constant *prologue = unwrap<Constant>(prologueData);
+  F->setPrologueData(prologue);
+}
+
 void LLVMAddAttributeAtIndex(LLVMValueRef F, LLVMAttributeIndex Idx,
                              LLVMAttributeRef A) {
   unwrap<Function>(F)->addAttributeAtIndex(Idx, unwrap(A));

llvm/test/Bindings/llvm-c/echo.ll

@@ -334,6 +334,20 @@ define void @test_fast_math_flags_call_outer(float %a) {
   ret void
 }
 
+define void @test_func_prefix_data_01() prefix i32 123 {
+  ret void
+}
+
+define void @test_func_prefix_data_02() prefix i64 2000 {
+  ret void
+}
+
+%func_prolog_struct = type <{ i8, i8, ptr }>
+
+define void @test_func_prologue_data_01() prologue %func_prolog_struct <{ i8 235, i8 8, ptr zeroinitializer}> {
+  ret void
+}
+
 !llvm.dbg.cu = !{!0, !2}
 !llvm.module.flags = !{!3}
 

llvm/tools/llvm-c-test/echo.cpp

@@ -1397,6 +1397,14 @@ static void clone_symbols(LLVMModuleRef Src, LLVMModuleRef M) {
     }
     LLVMDisposeValueMetadataEntries(AllMetadata);
 
+    // Copy any prefix data that may be on the function
+    if (LLVMHasPrefixData(Cur))
+      LLVMSetPrefixData(Fun, clone_constant(LLVMGetPrefixData(Cur), M));
+
+    // Copy any prologue data that may be on the function
+    if (LLVMHasPrologueData(Cur))
+      LLVMSetPrologueData(Fun, clone_constant(LLVMGetPrologueData(Cur), M));
+
     FunCloner FC(Cur, Fun);
     FC.CloneBBs(Cur);