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C ABI: Add C support for passing structs of floats to an extern function

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Currently this does not handle returning these structs yet.

Related: #1481
This commit is contained in:
Timon Kruiper
2020-05-28 19:45:11 +02:00
committed by Andrew Kelley
parent 34101127c6
commit 6e89692d81
3 changed files with 134 additions and 0 deletions
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72
src/codegen.cpp
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@@ -2062,6 +2062,78 @@ static bool iter_function_params_c_abi(CodeGen *g, ZigType *fn_type, FnWalk *fn_
}
}
return true;
} else if (abi_class == X64CABIClass_SSE) {
// For now only handle structs with only floats/doubles in it.
if (ty->id != ZigTypeIdStruct) {
if (source_node != nullptr) {
give_up_with_c_abi_error(g, source_node);
}
// otherwise allow codegen code to report a compile error
return false;
}
for (uint32_t i = 0; i < ty->data.structure.src_field_count; i += 1) {
if (ty->data.structure.fields[i]->type_entry->id != ZigTypeIdFloat) {
if (source_node != nullptr) {
give_up_with_c_abi_error(g, source_node);
}
// otherwise allow codegen code to report a compile error
return false;
}
}
// The SystemV ABI says that we have to setup 1 FP register per f64.
// So two f32 can be passed in one f64, but 3 f32 have to be passed in 2 FP registers.
// To achieve this with LLVM API, we pass multiple f64 parameters to the LLVM function if
// the type is bigger than 8 bytes.
// Example:
// extern struct {
// x: f32,
// y: f32,
// z: f32,
// };
// const ptr = (*f64)*Struct;
// Register 1: ptr.*
// Register 2: (ptr + 1).*
// One floating point register per f64 or 2 f32's
size_t number_of_fp_regs = (size_t)ceilf((float)ty_size / (float)8);
switch (fn_walk->id) {
case FnWalkIdAttrs: {
fn_walk->data.attrs.gen_i += 1;
break;
}
case FnWalkIdCall: {
LLVMValueRef f64_ptr_to_struct = LLVMBuildBitCast(g->builder, val, LLVMPointerType(LLVMDoubleType(), 0), "");
for (uint32_t i = 0; i < number_of_fp_regs; i += 1) {
LLVMValueRef index = LLVMConstInt(g->builtin_types.entry_usize->llvm_type, i, false);
LLVMValueRef indices[] = { index };
LLVMValueRef adjusted_ptr_to_struct = LLVMBuildInBoundsGEP(g->builder, f64_ptr_to_struct, indices, 1, "");
LLVMValueRef loaded = LLVMBuildLoad(g->builder, adjusted_ptr_to_struct, "");
fn_walk->data.call.gen_param_values->append(loaded);
}
break;
}
case FnWalkIdTypes: {
for (uint32_t i = 0; i < number_of_fp_regs; i += 1) {
fn_walk->data.types.gen_param_types->append(get_llvm_type(g, g->builtin_types.entry_f64));
fn_walk->data.types.param_di_types->append(get_llvm_di_type(g, g->builtin_types.entry_f64));
}
break;
}
case FnWalkIdVars:
case FnWalkIdInits: {
// TODO: Handle exporting functions
if (source_node != nullptr) {
give_up_with_c_abi_error(g, source_node);
}
// otherwise allow codegen code to report a compile error
return false;
}
}
return true;
}
}
if (source_node != nullptr) {