diff options
| -rw-r--r-- | src/tools/miri/README.md | 13 | ||||
| -rw-r--r-- | src/tools/miri/src/bin/miri.rs | 2 | ||||
| -rw-r--r-- | src/tools/miri/src/eval.rs | 3 | ||||
| -rw-r--r-- | src/tools/miri/src/machine.rs | 4 | ||||
| -rw-r--r-- | src/tools/miri/src/math.rs | 2 |
5 files changed, 18 insertions, 6 deletions
diff --git a/src/tools/miri/README.md b/src/tools/miri/README.md index 7816ce1ac56..7ccd27d7b83 100644 --- a/src/tools/miri/README.md +++ b/src/tools/miri/README.md @@ -286,11 +286,6 @@ environment variable. We first document the most relevant and most commonly used specific circumstances, but Miri's behavior will also be more stable across versions and targets. This is equivalent to `-Zmiri-fixed-schedule -Zmiri-compare-exchange-weak-failure-rate=0.0 -Zmiri-address-reuse-cross-thread-rate=0.0 -Zmiri-disable-weak-memory-emulation`. -* `-Zmiri-deterministic-floats` makes Miri's floating-point behavior fully deterministic. This means - that operations will always return the preferred NaN, imprecise operations will not have any - random error applied to them, and `min`/`max` as "maybe fused" multiply-add all behave - deterministically. Note that Miri still uses host floats for some operations, so behavior can - still differ depending on the host target and setup. * `-Zmiri-disable-isolation` disables host isolation. As a consequence, the program has access to host resources such as environment variables, file systems, and randomness. @@ -324,6 +319,8 @@ environment variable. We first document the most relevant and most commonly used Can be used without a value; in that case the range defaults to `0..64`. * `-Zmiri-many-seeds-keep-going` tells Miri to really try all the seeds in the given range, even if a failing seed has already been found. This is useful to determine which fraction of seeds fails. +* `-Zmiri-no-extra-rounding-error` stops Miri from adding extra rounding errors to float operations + that do not have a guaranteed precision. * `-Zmiri-num-cpus` states the number of available CPUs to be reported by miri. By default, the number of available CPUs is `1`. Note that this flag does not affect how miri handles threads in any way. @@ -376,6 +373,12 @@ to Miri failing to detect cases of undefined behavior in a program. will always fail and `0.0` means it will never fail. Note that setting it to `1.0` will likely cause hangs, since it means programs using `compare_exchange_weak` cannot make progress. +* `-Zmiri-deterministic-floats` makes Miri's floating-point behavior fully deterministic. This means + that operations will always return the preferred NaN, imprecise operations will not have any + random error applied to them, and `min`/`max` and "maybe fused" multiply-add all behave + deterministically. Note that Miri still uses host floats for some operations, so behavior can + still differ depending on the host target and setup. See `-Zmiri-no-extra-rounding-error` for + a flag that specifically only disables the random error. * `-Zmiri-disable-alignment-check` disables checking pointer alignment, so you can focus on other failures, but it means Miri can miss bugs in your program. Using this flag is **unsound**. diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs index 5d9c05807b8..89fa980ff64 100644 --- a/src/tools/miri/src/bin/miri.rs +++ b/src/tools/miri/src/bin/miri.rs @@ -562,6 +562,8 @@ fn main() { miri_config.force_intrinsic_fallback = true; } else if arg == "-Zmiri-deterministic-floats" { miri_config.float_nondet = false; + } else if arg == "-Zmiri-no-extra-rounding-error" { + miri_config.float_rounding_error = false; } else if arg == "-Zmiri-strict-provenance" { miri_config.provenance_mode = ProvenanceMode::Strict; } else if arg == "-Zmiri-permissive-provenance" { diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs index be6404f64e8..3c80e60b772 100644 --- a/src/tools/miri/src/eval.rs +++ b/src/tools/miri/src/eval.rs @@ -170,6 +170,8 @@ pub struct MiriConfig { pub force_intrinsic_fallback: bool, /// Whether floating-point operations can behave non-deterministically. pub float_nondet: bool, + /// Whether floating-point operations can have a non-deterministic rounding error. + pub float_rounding_error: bool, } impl Default for MiriConfig { @@ -211,6 +213,7 @@ impl Default for MiriConfig { fixed_scheduling: false, force_intrinsic_fallback: false, float_nondet: true, + float_rounding_error: true, } } } diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs index e3e7b0b88a7..ce33c870b4b 100644 --- a/src/tools/miri/src/machine.rs +++ b/src/tools/miri/src/machine.rs @@ -617,6 +617,8 @@ pub struct MiriMachine<'tcx> { /// Whether floating-point operations can behave non-deterministically. pub float_nondet: bool, + /// Whether floating-point operations can have a non-deterministic rounding error. + pub float_rounding_error: bool, } impl<'tcx> MiriMachine<'tcx> { @@ -775,6 +777,7 @@ impl<'tcx> MiriMachine<'tcx> { mangle_internal_symbol_cache: Default::default(), force_intrinsic_fallback: config.force_intrinsic_fallback, float_nondet: config.float_nondet, + float_rounding_error: config.float_rounding_error, } } @@ -951,6 +954,7 @@ impl VisitProvenance for MiriMachine<'_> { mangle_internal_symbol_cache: _, force_intrinsic_fallback: _, float_nondet: _, + float_rounding_error: _, } = self; threads.visit_provenance(visit); diff --git a/src/tools/miri/src/math.rs b/src/tools/miri/src/math.rs index cf16a5676d6..e9e5a1070c9 100644 --- a/src/tools/miri/src/math.rs +++ b/src/tools/miri/src/math.rs @@ -15,7 +15,7 @@ pub(crate) fn apply_random_float_error<F: rustc_apfloat::Float>( val: F, err_scale: i32, ) -> F { - if !ecx.machine.float_nondet { + if !ecx.machine.float_nondet || !ecx.machine.float_rounding_error { return val; } |