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translate-c: Improve function pointer handling

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Omit address-of operator if operand is a function.

Improve handling of function-call translation when using function pointers

Fixes #4124
This commit is contained in:
Evan Haas 2021-02-05 15:37:18 -08:00 committed by Veikka Tuominen
parent 1adac0a55b
commit 221f1d898c
6 changed files with 107 additions and 21 deletions
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5
src/clang.zig
View File

@ -848,7 +848,10 @@ pub const UnaryOperator = opaque {
extern fn ZigClangUnaryOperator_getBeginLoc(*const UnaryOperator) SourceLocation;
};
pub const ValueDecl = opaque {};
pub const ValueDecl = opaque {
pub const getType = ZigClangValueDecl_getType;
extern fn ZigClangValueDecl_getType(*const ValueDecl) QualType;
};
pub const VarDecl = opaque {
pub const getLocation = ZigClangVarDecl_getLocation;

56
src/translate_c.zig
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@ -3208,6 +3208,38 @@ fn transArrayAccess(rp: RestorePoint, scope: *Scope, stmt: *const clang.ArraySub
return maybeSuppressResult(rp, scope, result_used, &node.base);
}
/// Check if an expression is ultimately a reference to a function declaration
/// (which means it should not be unwrapped with `.?` in translated code)
fn cIsFunctionDeclRef(expr: *const clang.Expr) bool {
switch (expr.getStmtClass()) {
.ParenExprClass => {
const op_expr = @ptrCast(*const clang.ParenExpr, expr).getSubExpr();
return cIsFunctionDeclRef(op_expr);
},
.DeclRefExprClass => {
const decl_ref = @ptrCast(*const clang.DeclRefExpr, expr);
const value_decl = decl_ref.getDecl();
const qt = value_decl.getType();
return qualTypeChildIsFnProto(qt);
},
.ImplicitCastExprClass => {
const implicit_cast = @ptrCast(*const clang.ImplicitCastExpr, expr);
const cast_kind = implicit_cast.getCastKind();
if (cast_kind == .BuiltinFnToFnPtr) return true;
if (cast_kind == .FunctionToPointerDecay) {
return cIsFunctionDeclRef(implicit_cast.getSubExpr());
}
return false;
},
.UnaryOperatorClass => {
const un_op = @ptrCast(*const clang.UnaryOperator, expr);
const opcode = un_op.getOpcode();
return (opcode == .AddrOf or opcode == .Deref) and cIsFunctionDeclRef(un_op.getSubExpr());
},
else => return false,
}
}
fn transCallExpr(rp: RestorePoint, scope: *Scope, stmt: *const clang.CallExpr, result_used: ResultUsed) TransError!*ast.Node {
const callee = stmt.getCallee();
var raw_fn_expr = try transExpr(rp, scope, callee, .used, .r_value);
@ -3215,24 +3247,9 @@ fn transCallExpr(rp: RestorePoint, scope: *Scope, stmt: *const clang.CallExpr, r
var is_ptr = false;
const fn_ty = qualTypeGetFnProto(callee.getType(), &is_ptr);
const fn_expr = if (is_ptr and fn_ty != null) blk: {
if (callee.getStmtClass() == .ImplicitCastExprClass) {
const implicit_cast = @ptrCast(*const clang.ImplicitCastExpr, callee);
const cast_kind = implicit_cast.getCastKind();
if (cast_kind == .BuiltinFnToFnPtr) break :blk raw_fn_expr;
if (cast_kind == .FunctionToPointerDecay) {
const subexpr = implicit_cast.getSubExpr();
if (subexpr.getStmtClass() == .DeclRefExprClass) {
const decl_ref = @ptrCast(*const clang.DeclRefExpr, subexpr);
const named_decl = decl_ref.getFoundDecl();
if (@ptrCast(*const clang.Decl, named_decl).getKind() == .Function) {
break :blk raw_fn_expr;
}
}
}
}
break :blk try transCreateNodeUnwrapNull(rp.c, raw_fn_expr);
} else
const fn_expr = if (is_ptr and fn_ty != null and !cIsFunctionDeclRef(callee))
try transCreateNodeUnwrapNull(rp.c, raw_fn_expr)
else
raw_fn_expr;
const num_args = stmt.getNumArgs();
@ -3379,6 +3396,9 @@ fn transUnaryOperator(rp: RestorePoint, scope: *Scope, stmt: *const clang.UnaryO
else
return transCreatePreCrement(rp, scope, stmt, .AssignSub, .MinusEqual, "-=", used),
.AddrOf => {
if (cIsFunctionDeclRef(op_expr)) {
return transExpr(rp, scope, op_expr, used, .r_value);
}
const op_node = try transCreateNodeSimplePrefixOp(rp.c, .AddressOf, .Ampersand, "&");
op_node.rhs = try transExpr(rp, scope, op_expr, used, .r_value);
return &op_node.base;

5
src/zig_clang.cpp
View File

@ -2773,6 +2773,11 @@ struct ZigClangSourceLocation ZigClangUnaryOperator_getBeginLoc(const struct Zig
return bitcast(casted->getBeginLoc());
}
struct ZigClangQualType ZigClangValueDecl_getType(const struct ZigClangValueDecl *self) {
auto casted = reinterpret_cast<const clang::ValueDecl *>(self);
return bitcast(casted->getType());
}
const struct ZigClangExpr *ZigClangWhileStmt_getCond(const struct ZigClangWhileStmt *self) {
auto casted = reinterpret_cast<const clang::WhileStmt *>(self);
return reinterpret_cast<const struct ZigClangExpr *>(casted->getCond());

2
src/zig_clang.h
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@ -1200,6 +1200,8 @@ ZIG_EXTERN_C struct ZigClangQualType ZigClangUnaryOperator_getType(const struct
ZIG_EXTERN_C const struct ZigClangExpr *ZigClangUnaryOperator_getSubExpr(const struct ZigClangUnaryOperator *);
ZIG_EXTERN_C struct ZigClangSourceLocation ZigClangUnaryOperator_getBeginLoc(const struct ZigClangUnaryOperator *);
ZIG_EXTERN_C struct ZigClangQualType ZigClangValueDecl_getType(const struct ZigClangValueDecl *);
ZIG_EXTERN_C const struct ZigClangExpr *ZigClangWhileStmt_getCond(const struct ZigClangWhileStmt *);
ZIG_EXTERN_C const struct ZigClangStmt *ZigClangWhileStmt_getBody(const struct ZigClangWhileStmt *);

56
test/run_translated_c.zig
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@ -818,4 +818,60 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {
\\ return 0;
\\}
, "");
cases.add("Address of function is no-op",
\\#include <stdlib.h>
\\#include <stdbool.h>
\\typedef int (*myfunc)(int);
\\int a(int arg) { return arg + 1;}
\\int b(int arg) { return arg + 2;}
\\int caller(myfunc fn, int arg) {
\\ return fn(arg);
\\}
\\int main() {
\\ myfunc arr[3] = {&a, &b, a};
\\ myfunc foo = a;
\\ myfunc bar = &(a);
\\ if (foo != bar) abort();
\\ if (arr[0] == arr[1]) abort();
\\ if (arr[0] != arr[2]) abort();
\\ if (caller(b, 40) != 42) abort();
\\ if (caller(&b, 40) != 42) abort();
\\ return 0;
\\}
, "");
cases.add("Obscure ways of calling functions; issue #4124",
\\#include <stdlib.h>
\\static int add(int a, int b) {
\\ return a + b;
\\}
\\typedef int (*adder)(int, int);
\\typedef void (*funcptr)(void);
\\int main() {
\\ if ((add)(1, 2) != 3) abort();
\\ if ((&add)(1, 2) != 3) abort();
\\ if (add(3, 1) != 4) abort();
\\ if ((*add)(2, 3) != 5) abort();
\\ if ((**add)(7, -1) != 6) abort();
\\ if ((***add)(-2, 9) != 7) abort();
\\
\\ int (*ptr)(int a, int b);
\\ ptr = add;
\\
\\ if (ptr(1, 2) != 3) abort();
\\ if ((*ptr)(3, 1) != 4) abort();
\\ if ((**ptr)(2, 3) != 5) abort();
\\ if ((***ptr)(7, -1) != 6) abort();
\\ if ((****ptr)(-2, 9) != 7) abort();
\\
\\ funcptr addr1 = (funcptr)(add);
\\ funcptr addr2 = (funcptr)(&add);
\\
\\ if (addr1 != addr2) abort();
\\ if (((int(*)(int, int))addr1)(1, 2) != 3) abort();
\\ if (((adder)addr2)(1, 2) != 3) abort();
\\ return 0;
\\}
, "");
}

4
test/translate_c.zig
View File

@ -2802,8 +2802,8 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
\\ fn_f64(3);
\\ fn_bool(@as(c_int, 123) != 0);
\\ fn_bool(@as(c_int, 0) != 0);
\\ fn_bool(@ptrToInt(&fn_int) != 0);
\\ fn_int(@intCast(c_int, @ptrToInt(&fn_int)));
\\ fn_bool(@ptrToInt(fn_int) != 0);
\\ fn_int(@intCast(c_int, @ptrToInt(fn_int)));
\\ fn_ptr(@intToPtr(?*c_void, @as(c_int, 42)));
\\}
});