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souper-harvest: Do not generate assignments of constants

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It turns out that Souper does not allow a constant to be assigned to a variable,
they may only be used as operands. The 2.0.0 version of the `souper-ir` crate
correctly reflects this. In the `cranelift_codegen::souper_harvest` module, we
need to modify our Souper IR harvester so that it delays converting `iconst` and
`bconst` into Souper IR until their values are used as operands. Finally, some
unit tests in the `peepmatic-souper` crate need some small updates as well.
This commit is contained in:
Nick Fitzgerald
2020-10-15 17:00:02 -07:00
parent 09662fa716
commit f7cf771ee6
5 changed files with 60 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
Cargo.lock generated
View File

@@ -1989,9 +1989,9 @@ checksum = "fbee7696b84bbf3d89a1c2eccff0850e3047ed46bfcd2e92c29a2d074d57e252"
[[package]]
name = "souper-ir"
version = "1.0.0"
version = "2.0.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "163cc2bdd8a66cbaccdf06a6b476689a97e928883e09bffbe06fd5945842a83f"
checksum = "1c7eaed476845a4755001a900e0412dabd356d312ddc35dd32ff91de266b1558"
dependencies = [
"id-arena",
]

2
cranelift/codegen/Cargo.toml
View File

@@ -29,7 +29,7 @@ peepmatic = { path = "../peepmatic", optional = true, version = "0.68.0" }
peepmatic-traits = { path = "../peepmatic/crates/traits", optional = true, version = "0.68.0" }
peepmatic-runtime = { path = "../peepmatic/crates/runtime", optional = true, version = "0.68.0" }
regalloc = { version = "0.0.31" }
souper-ir = { version = "1", optional = true }
souper-ir = { version = "2.0.0", optional = true }
wast = { version = "28.0.0", optional = true }
# It is a goal of the cranelift-codegen crate to have minimal external dependencies.
# Please don't add any unless they are essential to the task of creating binary

68
cranelift/codegen/src/souper_harvest.rs
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@@ -142,7 +142,49 @@ fn harvest_candidate_lhs(
let souper_assignment_rhs = match func.dfg.value_def(val) {
ir::ValueDef::Result(inst, 0) => {
let args = func.dfg.inst_args(inst);
let arg = |allocs: &mut Allocs, n| allocs.ir_to_souper_val[&args[n]].into();
// Get the n^th argument as a souper operand.
let arg = |allocs: &mut Allocs, n| {
let arg = args[n];
if let Some(a) = allocs.ir_to_souper_val.get(&arg).copied() {
a.into()
} else {
// The only arguments we get that we haven't already
// converted into a souper instruction are `iconst`s and
// `bconst`s. This is because souper only allows
// constants as operands, and it doesn't allow assigning
// constants to a variable name. So we lazily convert
// `iconst`s and `bconst`s into souper operands here,
// when they are actually used.
match func.dfg.value_def(arg) {
ir::ValueDef::Result(inst, 0) => match func.dfg[inst] {
ir::InstructionData::UnaryImm { opcode, imm } => {
debug_assert_eq!(opcode, ir::Opcode::Iconst);
let imm: i64 = imm.into();
ast::Operand::Constant(ast::Constant {
value: imm.into(),
r#type: souper_type_of(&func.dfg, arg),
})
}
ir::InstructionData::UnaryBool { opcode, imm } => {
debug_assert_eq!(opcode, ir::Opcode::Iconst);
ast::Operand::Constant(ast::Constant {
value: imm.into(),
r#type: souper_type_of(&func.dfg, arg),
})
}
_ => unreachable!(
"only iconst and bconst instructions \
aren't in `ir_to_souper_val`"
),
},
_ => unreachable!(
"only iconst and bconst instructions \
aren't in `ir_to_souper_val`"
),
}
}
};
match (func.dfg[inst].opcode(), &func.dfg[inst]) {
(ir::Opcode::Iadd, _) => {
@@ -421,23 +463,13 @@ fn harvest_candidate_lhs(
let b = arg(allocs, 1);
ast::Instruction::UsubSat { a, b }.into()
}
(ir::Opcode::Iconst, ir::InstructionData::UnaryImm { imm, .. }) => {
let value: i64 = (*imm).into();
let value: i128 = value.into();
ast::Constant {
value,
r#type: souper_type_of(&func.dfg, val),
}
.into()
}
(ir::Opcode::Bconst, ir::InstructionData::UnaryBool { imm, .. }) => {
let value = *imm as i128;
ast::Constant {
value,
r#type: souper_type_of(&func.dfg, val),
}
.into()
}
// Because Souper doesn't allow constants to be on the right
// hand side of an assignment (i.e. `%0:i32 = 1234` is
// disallowed) we have to ignore `iconst` and `bconst`
// instructions until we process them as operands for some
// other instruction. See the `arg` closure above for
// details.
(ir::Opcode::Iconst, _) | (ir::Opcode::Bconst, _) => return,
_ => ast::AssignmentRhs::Var,
}
}

2
cranelift/peepmatic/crates/souper/Cargo.toml
View File

@@ -10,7 +10,7 @@ description = "Converting Souper optimizations into Peepmatic DSL"
[dependencies]
anyhow = "1"
souper-ir = { version = "1", features = ["parse"] }
souper-ir = { version = "2.0.0", features = ["parse"] }
log = "0.4.8"
[dev-dependencies]

19
cranelift/peepmatic/crates/souper/src/lib.rs
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@@ -174,7 +174,6 @@ fn convert_operand(
}
Some(format!("{}", convert_name(&assn.name)))
}
ast::AssignmentRhs::Constant(c) => Some(format!("{}", c.value)),
ast::AssignmentRhs::Instruction(inst) => match inst {
// Unsupported instructions.
ast::Instruction::Bswap { .. }
@@ -619,8 +618,7 @@ mod tests {
"
%0:i64 = var
%1:i32 = trunc %0
%2:i32 = 0
cand %1 %2
cand %1 0
",
"\
(=> (when (ireduce {i32} $v0)
@@ -631,8 +629,7 @@ mod tests {
"
%0:i32 = var
%1:i64 = sext %0
%2:i64 = 0
cand %1 %2
cand %1 0
",
"\
(=> (when (sextend {i64} $v0)
@@ -643,8 +640,7 @@ mod tests {
"
%0:i32 = var
%1:i64 = zext %0
%2:i64 = 0
cand %1 %2
cand %1 0
",
"\
(=> (when (uextend {i64} $v0)
@@ -677,8 +673,7 @@ mod tests {
%1:i32 = var
%2:i1 = eq %0, %1
%3:i32 = zext %2
%4:i32 = 0
cand %3 %4
cand %3 0
",
"\
(=> (when (bint (icmp eq $v0 $v1))
@@ -693,8 +688,7 @@ mod tests {
"
%0:i32 = var
%1:i32 = add %0, 1
%2:i32 = 0
cand %1 %2
cand %1 0
",
"\
(=> (when (iadd_imm 1 $v0)
@@ -705,8 +699,7 @@ mod tests {
"
%0:i32 = var
%1:i32 = add 1, %0
%2:i32 = 0
cand %1 %2
cand %1 0
",
"\
(=> (when (iadd_imm 1 $v0)