From 5a4561749a18fa96691f9cf79699e6ab2f1f7b2c Mon Sep 17 00:00:00 2001 From: Catherine Flores Date: Tue, 1 Aug 2023 15:35:12 +0000 Subject: Add new intrinsic `is_constant` and optimize `pow` Fix overflow check Make MIRI choose the path randomly and rename the intrinsic Add back test Add miri test and make it operate on `ptr` Define `llvm.is.constant` for primitives Update MIRI comment and fix test in stage2 Add const eval test Clarify that both branches must have the same side effects guaranteed non guarantee use immediate type instead Co-Authored-By: Ralf Jung --- src/tools/miri/src/shims/intrinsics/mod.rs | 12 ++++++++++++ src/tools/miri/tests/pass/intrinsics.rs | 15 +++++++++++++++ 2 files changed, 27 insertions(+) (limited to 'src/tools') diff --git a/src/tools/miri/src/shims/intrinsics/mod.rs b/src/tools/miri/src/shims/intrinsics/mod.rs index a1db7bf74f2..8edc0a4220d 100644 --- a/src/tools/miri/src/shims/intrinsics/mod.rs +++ b/src/tools/miri/src/shims/intrinsics/mod.rs @@ -5,6 +5,7 @@ use std::iter; use log::trace; +use rand::Rng; use rustc_apfloat::{Float, Round}; use rustc_middle::ty::layout::LayoutOf; use rustc_middle::{ @@ -141,6 +142,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> { this.write_pointer(Pointer::new(ptr.provenance, masked_addr), dest)?; } + // We want to return either `true` or `false` at random, or else something like + // ``` + // if !is_val_statically_known(0) { unreachable_unchecked(); } + // ``` + // Would not be considered UB, or the other way around (`is_val_statically_known(0)`). + "is_val_statically_known" => { + let [_] = check_arg_count(args)?; + let branch: bool = this.machine.rng.get_mut().gen(); + this.write_scalar(Scalar::from_bool(branch), dest)?; + } + // Floating-point operations "fabsf32" => { let [f] = check_arg_count(args)?; diff --git a/src/tools/miri/tests/pass/intrinsics.rs b/src/tools/miri/tests/pass/intrinsics.rs index 8c6eeab2219..8e46bd7ad48 100644 --- a/src/tools/miri/tests/pass/intrinsics.rs +++ b/src/tools/miri/tests/pass/intrinsics.rs @@ -33,6 +33,21 @@ fn main() { assert_eq!(intrinsics::likely(false), false); assert_eq!(intrinsics::unlikely(true), true); + let mut saw_true = false; + let mut saw_false = false; + + for _ in 0..50 { + if unsafe { intrinsics::is_val_statically_known(0) } { + saw_true = true; + } else { + saw_false = true; + } + } + assert!( + saw_true && saw_false, + "`is_val_statically_known` failed to return both true and false. Congrats, you won the lottery!" + ); + intrinsics::forget(Bomb); let _v = intrinsics::discriminant_value(&Some(())); -- cgit 1.4.1-3-g733a5