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stage2 LLVM backend: fix bitcast

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Properly handle when the operand type, the result type, or both, are
by-ref values.
This commit is contained in:
Andrew Kelley 2021-10-26 16:42:44 -07:00
parent f890de6294
commit 11a60e8779
3 changed files with 33 additions and 9 deletions
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30
src/codegen/llvm.zig
View File

@ -3201,14 +3201,23 @@ pub const FuncGen = struct {
const operand = try self.resolveInst(ty_op.operand);
const operand_ty = self.air.typeOf(ty_op.operand);
const inst_ty = self.air.typeOfIndex(inst);
const operand_is_ref = isByRef(operand_ty);
const result_is_ref = isByRef(inst_ty);
const llvm_dest_ty = try self.dg.llvmType(inst_ty);
if (operand_is_ref and result_is_ref) {
// They are both pointers; just do a bitcast on the pointers :)
return self.builder.buildBitCast(operand, llvm_dest_ty.pointerType(0), "");
}
if (operand_ty.zigTypeTag() == .Int and inst_ty.zigTypeTag() == .Pointer) {
return self.builder.buildIntToPtr(operand, llvm_dest_ty, "");
} else if (operand_ty.zigTypeTag() == .Vector and inst_ty.zigTypeTag() == .Array) {
}
if (operand_ty.zigTypeTag() == .Vector and inst_ty.zigTypeTag() == .Array) {
const target = self.dg.module.getTarget();
const elem_ty = operand_ty.childType();
if (!isByRef(inst_ty)) {
if (!result_is_ref) {
return self.dg.todo("implement bitcast vector to non-ref array", .{});
}
const array_ptr = self.buildAlloca(llvm_dest_ty);
@ -3239,7 +3248,7 @@ pub const FuncGen = struct {
const target = self.dg.module.getTarget();
const elem_ty = operand_ty.childType();
const llvm_vector_ty = try self.dg.llvmType(inst_ty);
if (!isByRef(operand_ty)) {
if (!operand_is_ref) {
return self.dg.todo("implement bitcast non-ref array to vector", .{});
}
@ -3274,6 +3283,21 @@ pub const FuncGen = struct {
}
}
if (operand_is_ref) {
// Bitcast the operand pointer, then load.
const casted_ptr = self.builder.buildBitCast(operand, llvm_dest_ty.pointerType(0), "");
return self.builder.buildLoad(casted_ptr, "");
}
if (result_is_ref) {
// Bitcast the result pointer, then store.
const result_ptr = self.buildAlloca(llvm_dest_ty);
const operand_llvm_ty = try self.dg.llvmType(operand_ty);
const casted_ptr = self.builder.buildBitCast(result_ptr, operand_llvm_ty.pointerType(0), "");
_ = self.builder.buildStore(operand, casted_ptr);
return result_ptr;
}
return self.builder.buildBitCast(operand, llvm_dest_ty, "");
}

6
test/behavior/bitcast.zig
View File

@ -64,3 +64,9 @@ test "bitcast literal [4]u8 param to u32" {
const ip = @bitCast(u32, [_]u8{ 255, 255, 255, 255 });
try expect(ip == maxInt(u32));
}
test "bitcast generates a temporary value" {
var y = @as(u16, 0x55AA);
const x = @bitCast(u16, @bitCast([2]u8, y));
try expect(y == x);
}

6
test/behavior/bitcast_stage1.zig
View File

@ -129,9 +129,3 @@ test "triple level result location with bitcast sandwich passed as tuple element
};
try S.foo(.{@as(f64, @bitCast(f32, @as(u32, 0x414570A4)))});
}
test "bitcast generates a temporary value" {
var y = @as(u16, 0x55AA);
const x = @bitCast(u16, @bitCast([2]u8, y));
try expectEqual(y, x);
}