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Always take advantage of arithmetic identities
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17 changes: 17 additions & 0 deletions
17
src/test/mir-opt/div_overflow.const_dividend.PreCodegen.after.mir
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// MIR for `const_dividend` after PreCodegen | ||
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fn const_dividend(_1: i32) -> i32 { | ||
debug a => _1; // in scope 0 at $DIR/div_overflow.rs:+0:23: +0:24 | ||
let mut _0: i32; // return place in scope 0 at $DIR/div_overflow.rs:+0:34: +0:37 | ||
let mut _2: bool; // in scope 0 at $DIR/div_overflow.rs:+1:5: +1:12 | ||
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bb0: { | ||
_2 = Eq(_1, const 0_i32); // scope 0 at $DIR/div_overflow.rs:+1:5: +1:12 | ||
assert(!move _2, "attempt to divide `{}` by zero", const 256_i32) -> bb1; // scope 0 at $DIR/div_overflow.rs:+1:5: +1:12 | ||
} | ||
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bb1: { | ||
_0 = Div(const 256_i32, move _1); // scope 0 at $DIR/div_overflow.rs:+1:5: +1:12 | ||
return; // scope 0 at $DIR/div_overflow.rs:+2:2: +2:2 | ||
} | ||
} |
11 changes: 11 additions & 0 deletions
11
src/test/mir-opt/div_overflow.const_divisor.PreCodegen.after.mir
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// MIR for `const_divisor` after PreCodegen | ||
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fn const_divisor(_1: i32) -> i32 { | ||
debug a => _1; // in scope 0 at $DIR/div_overflow.rs:+0:22: +0:23 | ||
let mut _0: i32; // return place in scope 0 at $DIR/div_overflow.rs:+0:33: +0:36 | ||
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bb0: { | ||
_0 = Div(move _1, const 256_i32); // scope 0 at $DIR/div_overflow.rs:+1:5: +1:12 | ||
return; // scope 0 at $DIR/div_overflow.rs:+2:2: +2:2 | ||
} | ||
} |
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// compile-flags: -Copt-level=0 -Coverflow-checks=yes | ||
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// Tests that division with a const does not emit a panicking branch for overflow | ||
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// EMIT_MIR div_overflow.const_divisor.PreCodegen.after.mir | ||
pub fn const_divisor(a: i32) -> i32 { | ||
a / 256 | ||
} | ||
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// EMIT_MIR div_overflow.const_dividend.PreCodegen.after.mir | ||
pub fn const_dividend(a: i32) -> i32 { | ||
256 / a | ||
} | ||
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fn main() { | ||
const_divisor(123); | ||
const_dividend(123); | ||
} |