diff options
Diffstat (limited to 'compiler/rustc_codegen_gcc/src/intrinsic/mod.rs')
| -rw-r--r-- | compiler/rustc_codegen_gcc/src/intrinsic/mod.rs | 90 |
1 files changed, 55 insertions, 35 deletions
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs index 68a05d95ef7..c6681de68e2 100644 --- a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs +++ b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs @@ -967,34 +967,55 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> { } fn saturating_add(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>, signed: bool, width: u64) -> RValue<'gcc> { - let func = self.current_func.borrow().expect("func"); - + let result_type = lhs.get_type(); if signed { - // Algorithm from: https://stackoverflow.com/a/56531252/389119 - let after_block = func.new_block("after"); - let func_name = - match width { - 8 => "__builtin_add_overflow", - 16 => "__builtin_add_overflow", - 32 => "__builtin_sadd_overflow", - 64 => "__builtin_saddll_overflow", - 128 => "__builtin_add_overflow", - _ => unreachable!(), - }; - let overflow_func = self.context.get_builtin_function(func_name); - let result_type = lhs.get_type(); + // Based on algorithm from: https://stackoverflow.com/a/56531252/389119 + let func = self.current_func.borrow().expect("func"); let res = func.new_local(None, result_type, "saturating_sum"); - let overflow = self.overflow_call(overflow_func, &[lhs, rhs, res.get_address(None)], None); + let supports_native_type = self.is_native_int_type(result_type); + let overflow = + if supports_native_type { + let func_name = + match width { + 8 => "__builtin_add_overflow", + 16 => "__builtin_add_overflow", + 32 => "__builtin_sadd_overflow", + 64 => "__builtin_saddll_overflow", + 128 => "__builtin_add_overflow", + _ => unreachable!(), + }; + let overflow_func = self.context.get_builtin_function(func_name); + self.overflow_call(overflow_func, &[lhs, rhs, res.get_address(None)], None) + } + else { + let func_name = + match width { + 128 => "__rust_i128_addo", + _ => unreachable!(), + }; + let param_a = self.context.new_parameter(None, result_type, "a"); + let param_b = self.context.new_parameter(None, result_type, "b"); + let result_field = self.context.new_field(None, result_type, "result"); + let overflow_field = self.context.new_field(None, self.bool_type, "overflow"); + let return_type = self.context.new_struct_type(None, "result_overflow", &[result_field, overflow_field]); + let func = self.context.new_function(None, FunctionType::Extern, return_type.as_type(), &[param_a, param_b], func_name, false); + let result = self.context.new_call(None, func, &[lhs, rhs]); + let overflow = result.access_field(None, overflow_field); + let int_result = result.access_field(None, result_field); + self.llbb().add_assignment(None, res, int_result); + overflow + }; let then_block = func.new_block("then"); + let after_block = func.new_block("after"); - let unsigned_type = self.context.new_int_type(width as i32 / 8, false); - let shifted = self.context.new_cast(None, lhs, unsigned_type) >> self.context.new_rvalue_from_int(unsigned_type, width as i32 - 1); - let uint_max = self.context.new_unary_op(None, UnaryOp::BitwiseNegate, unsigned_type, - self.context.new_rvalue_from_int(unsigned_type, 0) - ); - let int_max = uint_max >> self.context.new_rvalue_one(unsigned_type); - then_block.add_assignment(None, res, self.context.new_cast(None, shifted + int_max, result_type)); + // Return `result_type`'s maximum or minimum value on overflow + // NOTE: convert the type to unsigned to have an unsigned shift. + let unsigned_type = result_type.to_unsigned(&self.cx); + let shifted = self.gcc_lshr(self.gcc_int_cast(lhs, unsigned_type), self.gcc_int(unsigned_type, width as i64 - 1)); + let uint_max = self.gcc_not(self.gcc_int(unsigned_type, 0)); + let int_max = self.gcc_lshr(uint_max, self.gcc_int(unsigned_type, 1)); + then_block.add_assignment(None, res, self.gcc_int_cast(self.gcc_add(shifted, int_max), result_type)); then_block.end_with_jump(None, after_block); self.llbb().end_with_conditional(None, overflow, then_block, after_block); @@ -1007,19 +1028,18 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> { } else { // Algorithm from: http://locklessinc.com/articles/sat_arithmetic/ - let res = lhs + rhs; - let res_type = res.get_type(); - let cond = self.context.new_comparison(None, ComparisonOp::LessThan, res, lhs); - let value = self.context.new_unary_op(None, UnaryOp::Minus, res_type, self.context.new_cast(None, cond, res_type)); - res | value + let res = self.gcc_add(lhs, rhs); + let cond = self.gcc_icmp(IntPredicate::IntULT, res, lhs); + let value = self.gcc_neg(self.gcc_int_cast(cond, result_type)); + self.gcc_or(res, value) } } // Algorithm from: https://locklessinc.com/articles/sat_arithmetic/ fn saturating_sub(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>, signed: bool, width: u64) -> RValue<'gcc> { + let result_type = lhs.get_type(); if signed { - // Also based on algorithm from: https://stackoverflow.com/a/56531252/389119 - let result_type = lhs.get_type(); + // Based on algorithm from: https://stackoverflow.com/a/56531252/389119 let func = self.current_func.borrow().expect("func"); let res = func.new_local(None, result_type, "saturating_diff"); let supports_native_type = self.is_native_int_type(result_type); @@ -1059,6 +1079,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> { let then_block = func.new_block("then"); let after_block = func.new_block("after"); + // Return `result_type`'s maximum or minimum value on overflow // NOTE: convert the type to unsigned to have an unsigned shift. let unsigned_type = result_type.to_unsigned(&self.cx); let shifted = self.gcc_lshr(self.gcc_int_cast(lhs, unsigned_type), self.gcc_int(unsigned_type, width as i64 - 1)); @@ -1076,11 +1097,10 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> { res.to_rvalue() } else { - let res = lhs - rhs; - let comparison = self.context.new_comparison(None, ComparisonOp::LessThanEquals, res, lhs); - let comparison = self.context.new_cast(None, comparison, lhs.get_type()); - let unary_op = self.context.new_unary_op(None, UnaryOp::Minus, comparison.get_type(), comparison); - self.and(res, unary_op) + let res = self.gcc_sub(lhs, rhs); + let comparison = self.gcc_icmp(IntPredicate::IntULE, res, lhs); + let value = self.gcc_neg(self.gcc_int_cast(comparison, result_type)); + self.gcc_and(res, value) } } } |