From 7d63efdb8c2d3b9ea25fa2bbb8703168d21483c8 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sat, 5 Oct 2024 17:05:47 +0200 Subject: [PATCH] fix GVN trying to transmute pointers to integers --- compiler/rustc_mir_transform/src/gvn.rs | 30 +++++++++++++++++----- tests/coverage/closure_macro.cov-map | 8 +++--- tests/coverage/closure_macro_async.cov-map | 8 +++--- 3 files changed, 31 insertions(+), 15 deletions(-) diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs index 50c9702cb9b..7707d0d51f1 100644 --- a/compiler/rustc_mir_transform/src/gvn.rs +++ b/compiler/rustc_mir_transform/src/gvn.rs @@ -103,7 +103,7 @@ use rustc_middle::ty::layout::{HasParamEnv, LayoutOf}; use rustc_middle::ty::{self, Ty, TyCtxt}; use rustc_span::DUMMY_SP; use rustc_span::def_id::DefId; -use rustc_target::abi::{self, Abi, FIRST_VARIANT, FieldIdx, Size, VariantIdx}; +use rustc_target::abi::{self, Abi, FIRST_VARIANT, FieldIdx, Primitive, Size, VariantIdx}; use smallvec::SmallVec; use tracing::{debug, instrument, trace}; @@ -568,13 +568,29 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { CastKind::Transmute => { let value = self.evaluated[value].as_ref()?; let to = self.ecx.layout_of(to).ok()?; - // `offset` for immediates only supports scalar/scalar-pair ABIs, - // so bail out if the target is not one. + // `offset` for immediates generally only supports projections that match the + // type of the immediate. However, as a HACK, we exploit that it can also do + // limited transmutes: it only works between types with the same layout, and + // cannot transmute pointers to integers. if value.as_mplace_or_imm().is_right() { - match (value.layout.abi, to.abi) { - (Abi::Scalar(..), Abi::Scalar(..)) => {} - (Abi::ScalarPair(..), Abi::ScalarPair(..)) => {} - _ => return None, + let can_transmute = match (value.layout.abi, to.abi) { + (Abi::Scalar(s1), Abi::Scalar(s2)) => { + s1.size(&self.ecx) == s2.size(&self.ecx) + && !matches!(s1.primitive(), Primitive::Pointer(..)) + } + (Abi::ScalarPair(a1, b1), Abi::ScalarPair(a2, b2)) => { + a1.size(&self.ecx) == a2.size(&self.ecx) && + b1.size(&self.ecx) == b2.size(&self.ecx) && + // The alignment of the second component determines its offset, so that also needs to match. + b1.align(&self.ecx) == b2.align(&self.ecx) && + // None of the inputs may be a pointer. + !matches!(a1.primitive(), Primitive::Pointer(..)) + && !matches!(b1.primitive(), Primitive::Pointer(..)) + } + _ => false, + }; + if !can_transmute { + return None; } } value.offset(Size::ZERO, to, &self.ecx).discard_err()? diff --git a/tests/coverage/closure_macro.cov-map b/tests/coverage/closure_macro.cov-map index eb5f94d1080..fb4a137d4c8 100644 --- a/tests/coverage/closure_macro.cov-map +++ b/tests/coverage/closure_macro.cov-map @@ -23,19 +23,19 @@ Number of file 0 mappings: 6 - Code(Counter(0)) at (prev + 3, 1) to (start + 0, 2) Function name: closure_macro::main::{closure#0} -Raw bytes (35): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 00, 05, 01, 10, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 16, 00, 00, 17, 00, 1e, 07, 02, 09, 00, 0a] +Raw bytes (35): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 0d, 05, 01, 10, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 16, 0d, 00, 17, 00, 1e, 07, 02, 09, 00, 0a] Number of files: 1 - file 0 => global file 1 Number of expressions: 3 - expression 0 operands: lhs = Counter(0), rhs = Counter(1) - expression 1 operands: lhs = Counter(1), rhs = Expression(2, Add) -- expression 2 operands: lhs = Counter(2), rhs = Zero +- expression 2 operands: lhs = Counter(2), rhs = Counter(3) Number of file 0 mappings: 5 - Code(Counter(0)) at (prev + 16, 28) to (start + 3, 33) - Code(Counter(1)) at (prev + 4, 17) to (start + 1, 39) - Code(Expression(0, Sub)) at (prev + 3, 17) to (start + 0, 22) = (c0 - c1) -- Code(Zero) at (prev + 0, 23) to (start + 0, 30) +- Code(Counter(3)) at (prev + 0, 23) to (start + 0, 30) - Code(Expression(1, Add)) at (prev + 2, 9) to (start + 0, 10) - = (c1 + (c2 + Zero)) + = (c1 + (c2 + c3)) diff --git a/tests/coverage/closure_macro_async.cov-map b/tests/coverage/closure_macro_async.cov-map index 4d0597f58bf..091e87909f9 100644 --- a/tests/coverage/closure_macro_async.cov-map +++ b/tests/coverage/closure_macro_async.cov-map @@ -31,19 +31,19 @@ Number of file 0 mappings: 6 - Code(Counter(0)) at (prev + 3, 1) to (start + 0, 2) Function name: closure_macro_async::test::{closure#0}::{closure#0} -Raw bytes (35): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 00, 05, 01, 15, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 16, 00, 00, 17, 00, 1e, 07, 02, 09, 00, 0a] +Raw bytes (35): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 0d, 05, 01, 15, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 16, 0d, 00, 17, 00, 1e, 07, 02, 09, 00, 0a] Number of files: 1 - file 0 => global file 1 Number of expressions: 3 - expression 0 operands: lhs = Counter(0), rhs = Counter(1) - expression 1 operands: lhs = Counter(1), rhs = Expression(2, Add) -- expression 2 operands: lhs = Counter(2), rhs = Zero +- expression 2 operands: lhs = Counter(2), rhs = Counter(3) Number of file 0 mappings: 5 - Code(Counter(0)) at (prev + 21, 28) to (start + 3, 33) - Code(Counter(1)) at (prev + 4, 17) to (start + 1, 39) - Code(Expression(0, Sub)) at (prev + 3, 17) to (start + 0, 22) = (c0 - c1) -- Code(Zero) at (prev + 0, 23) to (start + 0, 30) +- Code(Counter(3)) at (prev + 0, 23) to (start + 0, 30) - Code(Expression(1, Add)) at (prev + 2, 9) to (start + 0, 10) - = (c1 + (c2 + Zero)) + = (c1 + (c2 + c3))