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Rollup merge of #60745 - wesleywiser:const_prop_into_terminators, r=oli-obk

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Perform constant propagation into terminators

Perform constant propagation into MIR `Assert` and `SwitchInt` `Terminator`s which in some cases allows them to be removed by the branch simplification pass.

r? @oli-obk
This commit is contained in:
Mazdak Farrokhzad 2019-05-20 01:01:38 +02:00 • committed by GitHub
commit 5c84d779b2
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 152 additions and 73 deletions
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2
src/test/mir-opt/const_prop/array_index.rs
View file

@ -23,7 +23,7 @@ fn main() {
// bb0: {
// ...
// _5 = const true;
// assert(move _5, "index out of bounds: the len is move _4 but the index is _3") -> bb1;
// assert(const true, "index out of bounds: the len is move _4 but the index is _3") -> bb1;
// }
// bb1: {
// _1 = _2[_3];

2
src/test/mir-opt/const_prop/checked_add.rs
View file

@ -16,6 +16,6 @@ fn main() {
// bb0: {
// ...
// _2 = (const 2u32, const false);
// assert(!move (_2.1: bool), "attempt to add with overflow") -> bb1;
// assert(!const false, "attempt to add with overflow") -> bb1;
// }
// END rustc.main.ConstProp.after.mir

38
src/test/mir-opt/const_prop/switch_int.rs Normal file
View file

@ -0,0 +1,38 @@
#[inline(never)]
fn foo(_: i32) { }
fn main() {
match 1 {
1 => foo(0),
_ => foo(-1),
}
}
// END RUST SOURCE
// START rustc.main.ConstProp.before.mir
// bb0: {
// ...
// _1 = const 1i32;
// switchInt(_1) -> [1i32: bb1, otherwise: bb2];
// }
// END rustc.main.ConstProp.before.mir
// START rustc.main.ConstProp.after.mir
// bb0: {
// ...
// switchInt(const 1i32) -> [1i32: bb1, otherwise: bb2];
// }
// END rustc.main.ConstProp.after.mir
// START rustc.main.SimplifyBranches-after-const-prop.before.mir
// bb0: {
// ...
// _1 = const 1i32;
// switchInt(const 1i32) -> [1i32: bb1, otherwise: bb2];
// }
// END rustc.main.SimplifyBranches-after-const-prop.before.mir
// START rustc.main.SimplifyBranches-after-const-prop.after.mir
// bb0: {
// ...
// _1 = const 1i32;
// goto -> bb1;
// }
// END rustc.main.SimplifyBranches-after-const-prop.after.mir

8
src/test/mir-opt/simplify_if.rs
View file

@ -5,15 +5,15 @@ fn main() {
}
// END RUST SOURCE
// START rustc.main.SimplifyBranches-after-copy-prop.before.mir
// START rustc.main.SimplifyBranches-after-const-prop.before.mir
// bb0: {
// ...
// switchInt(const false) -> [false: bb3, otherwise: bb1];
// }
// END rustc.main.SimplifyBranches-after-copy-prop.before.mir
// START rustc.main.SimplifyBranches-after-copy-prop.after.mir
// END rustc.main.SimplifyBranches-after-const-prop.before.mir
// START rustc.main.SimplifyBranches-after-const-prop.after.mir
// bb0: {
// ...
// goto -> bb3;
// }
// END rustc.main.SimplifyBranches-after-copy-prop.after.mir
// END rustc.main.SimplifyBranches-after-const-prop.after.mir