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* nativeGen/aarch64: Fix handling of subword valuesBen Gamari2021-12-021-1/+1
| | | | | | | | | | | | | | | | Here we rework the handling of sub-word operations in the AArch64 backend, fixing a number of bugs and inconsistencies. In short, we now impose the invariant that all subword values are represented in registers in zero-extended form. Signed arithmetic operations are then responsible for sign-extending as necessary. Possible future work: * Use `CMP`s extended register form to avoid burning an instruction in sign-extending the second operand. * Track sign-extension state of registers to elide redundant sign extensions in blocks with frequent sub-word signed arithmetic.
* cmm/opt: Fold away shifts larger than shiftee widthBen Gamari2021-12-021-2/+12
| | | | | This is necessary for lint-correctness since we no longer allow such shifts in Cmm.
* cmm: narrow when folding signed quotientsBen Gamari2021-12-021-2/+2
| | | | | | | | | | | | | | | | | | Previously the constant-folding behavior for MO_S_Quot and MO_S_Rem failed to narrow its arguments, meaning that a program like: %zx64(%quot(%lobits8(0x00e1::bits16), 3::bits8)) would be miscompiled. Specifically, this program should reduce as %lobits8(0x00e1::bits16) == -31 %quot(%lobits8(0x00e1::bits16), 3::bits8) == -10 %zx64(%quot(%lobits8(0x00e1::bits16), 3::bits8)) == 246 However, with this bug the `%lobits8(0x00e1::bits16)` would instead be treated as `+31`, resulting in the incorrect result of `75`. (cherry picked from commit 94e197e3dbb9a48991eb90a03b51ea13d39ba4cc)
* Delete ToDo about incorrect optimisation [skip ci]Peter Trommler2021-07-291-4/+0
| | | | | On big-endian systems a narrow after a load cannot be replaced with a narrow load.
* Cmm.Opt: Fix type of shift amount in constant foldingBen Gamari2021-07-231-2/+2
| | | | | | | | Previously the `MO_S_Quot` constant folding rule would incorrectly pass the shift amount of the same width as the shifted value. However, the machop's type expects the shift amount to be a Word. Fixes #20142.
* Re-export GHC.Bits from GHC.Prelude with custom shift implementation.Andreas Klebinger2021-04-091-1/+0
| | | | | | | This allows us to use the unsafe shifts in non-debug builds for performance. For older versions of base we instead export Data.Bits See also #19618
* C-- shift amount is always native size, not shiftee sizeJohn Ericson2021-01-221-2/+2
| | | | | This isn't a bug yet, because we only shift native-sized types, but I hope to change that.
* GHC.Cmm.Opt: Be stricter in results.Andreas Klebinger2020-12-081-51/+51
| | | | | | | | | | | | | Optimization either returns Nothing if nothing is to be done or `Just <cmmExpr>` otherwise. There is no point in being lazy in `cmmExpr`. We usually inspect this element so the thunk gets forced not long after. We might eliminate it as dead code once in a blue moon but that's not a case worth optimizing for. Overall the impact of this is rather low. As Cmm.Opt doesn't allocate much (compared to the rest of GHC) to begin with.
* DynFlags: disentangle OutputableSylvain Henry2020-08-121-1/+1
| | | | | | | | | - put panic related functions into GHC.Utils.Panic - put trace related functions using DynFlags in GHC.Driver.Ppr One step closer making Outputable fully independent of DynFlags. Bump haddock submodule
* GHC.Cmm.Opt: Handle MO_XX_ConvBen Gamari2020-05-151-0/+2
| | | | | | | | | This MachOp was introduced by 2c959a1894311e59cd2fd469c1967491c1e488f3 but a wildcard match in cmmMachOpFoldM hid the fact that it wasn't handled. Ideally we would eliminate the match but this appears to be a larger task. Fixes #18141.
* Modules: Utils and Data (#13009)Sylvain Henry2020-04-261-3/+3
| | | | | | | Update Haddock submodule Metric Increase: haddock.compiler
* Refactoring: use Platform instead of DynFlags when possibleSylvain Henry2020-03-191-46/+45
| | | | | | | | Metric Decrease: ManyConstructors T12707 T13035 T1969
* Modules: Driver (#13009)Sylvain Henry2020-02-211-1/+1
| | | | submodule updates: nofib, haddock
* Module hierarchy: Cmm (cf #13009)Sylvain Henry2020-01-251-0/+423