llvm-capstone/clang/test/CodeGen/builtin-abs.c
Sanjay Patel 74c7fb002f [CodeGen] use nsw negation for builtin abs
The clang builtins have the same semantics as the stdlib functions.
The stdlib functions are defined in section 7.20.6.1 of the C standard with:
"If the result cannot be represented, the behavior is undefined."

That lets us mark the negation with 'nsw' because "sub i32 0, INT_MIN" would
be UB/poison.

Differential Revision: https://reviews.llvm.org/D47202

llvm-svn: 333038
2018-05-22 23:02:13 +00:00

30 lines
827 B
C

// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm %s -o - | FileCheck %s
int absi(int x) {
// CHECK-LABEL: @absi(
// CHECK: [[NEG:%.*]] = sub nsw i32 0, [[X:%.*]]
// CHECK: [[CMP:%.*]] = icmp slt i32 [[X]], 0
// CHECK: [[SEL:%.*]] = select i1 [[CMP]], i32 [[NEG]], i32 [[X]]
//
return __builtin_abs(x);
}
long absl(long x) {
// CHECK-LABEL: @absl(
// CHECK: [[NEG:%.*]] = sub nsw i64 0, [[X:%.*]]
// CHECK: [[CMP:%.*]] = icmp slt i64 [[X]], 0
// CHECK: [[SEL:%.*]] = select i1 [[CMP]], i64 [[NEG]], i64 [[X]]
//
return __builtin_labs(x);
}
long long absll(long long x) {
// CHECK-LABEL: @absll(
// CHECK: [[NEG:%.*]] = sub nsw i64 0, [[X:%.*]]
// CHECK: [[CMP:%.*]] = icmp slt i64 [[X]], 0
// CHECK: [[SEL:%.*]] = select i1 [[CMP]], i64 [[NEG]], i64 [[X]]
//
return __builtin_llabs(x);
}