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Merge pull request #1930 from cfallin/spectre-heap

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Spectre mitigation on heap access overflow checks.
This commit is contained in:
Chris Fallin
2020-07-01 09:23:04 -07:00
committed by GitHub
parent f80c2abffb e694fb1312
commit a351fa52b5
9 changed files with 148 additions and 47 deletions
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6
cranelift/codegen/meta/src/isa/x86/encodings.rs
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@@ -1395,6 +1395,7 @@ fn define_alu(
let rotr = shared.by_name("rotr");
let rotr_imm = shared.by_name("rotr_imm");
let selectif = shared.by_name("selectif");
let selectif_spectre_guard = shared.by_name("selectif_spectre_guard");
let sshr = shared.by_name("sshr");
let sshr_imm = shared.by_name("sshr_imm");
let trueff = shared.by_name("trueff");
@@ -1608,6 +1609,11 @@ fn define_alu(
// Conditional move (a.k.a integer select).
e.enc_i32_i64(selectif, rec_cmov.opcodes(&CMOV_OVERFLOW));
// A Spectre-guard integer select is exactly the same as a selectif, but
// is not associated with any other legalization rules and is not
// recognized by any optimizations, so it must arrive here unmodified
// and in its original place.
e.enc_i32_i64(selectif_spectre_guard, rec_cmov.opcodes(&CMOV_OVERFLOW));
}
#[inline(never)]