[Git][ghc/ghc][master] 2 commits: testsuite: Mark MulMayOflo_full as broken rather than skipping

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
fd7ce39c by Ben Gamari at 2023-08-04T12:27:28-04:00
testsuite: Mark MulMayOflo_full as broken rather than skipping

To ensure that we don't accidentally fix it.

See #23742.

- - - - -
824092f2 by Ben Gamari at 2023-08-04T12:27:28-04:00
nativeGen/AArch64: Fix sign extension in MulMayOflo

Previously the 32-bit implementations of MulMayOflo would use the
a non-sensical sign-extension mode. Rewrite these to reflect what gcc 11
produces. Also similarly rework the 16- and 8-bit cases.

This now passes the MulMayOflo tests in ghc/test-primops> in all four
widths, including the precision tests.

Fixes #23721.

- - - - -


2 changed files:

- compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
- testsuite/tests/codeGen/should_run/all.T


Changes:

=====================================
compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
=====================================
@@ -1138,6 +1138,7 @@ getRegister' config plat expr
     isNbitEncodeable n_bits i = let shift = n_bits - 1 in (-1 `shiftL` shift) <= i && i < (1 `shiftL` shift)
 
     -- N.B. MUL does not set the overflow flag.
+    -- These implementations are based on output from GCC 11.
     do_mul_may_oflo :: Width -> CmmExpr -> CmmExpr -> NatM Register
     do_mul_may_oflo w at W64 x y = do
         (reg_x, _format_x, code_x) <- getSomeReg x
@@ -1151,31 +1152,47 @@ getRegister' config plat expr
             SMULH (OpReg w hi) (OpReg w reg_x) (OpReg w reg_y) `snocOL`
             CMP (OpReg w hi) (OpRegShift w lo SASR 63) `snocOL`
             CSET (OpReg w dst) NE)
+
+    do_mul_may_oflo W32 x y = do
+        (reg_x, _format_x, code_x) <- getSomeReg x
+        (reg_y, _format_y, code_y) <- getSomeReg y
+        tmp1 <- getNewRegNat II64
+        tmp2 <- getNewRegNat II64
+        return $ Any (intFormat W32) (\dst ->
+            code_x `appOL`
+            code_y `snocOL`
+            SMULL (OpReg W64 tmp1) (OpReg W32 reg_x) (OpReg W32 reg_y) `snocOL`
+            ASR (OpReg W64 tmp2) (OpReg W64 tmp1) (OpImm (ImmInt 31)) `snocOL`
+            CMP (OpReg W32 tmp2) (OpRegShift W32 tmp1 SASR 31) `snocOL`
+            CSET (OpReg W32 dst) NE)
+
     do_mul_may_oflo w x y = do
         (reg_x, _format_x, code_x) <- getSomeReg x
         (reg_y, _format_y, code_y) <- getSomeReg y
-        let tmp_w = case w of
-                      W32 -> W64
-                      W16 -> W32
-                      W8  -> W32
-                      _   -> panic "do_mul_may_oflo: impossible"
-        -- This will hold the product
-        tmp <- getNewRegNat (intFormat tmp_w)
-        let ext_mode = case w of
-                         W32 -> ESXTW
-                         W16 -> ESXTH
-                         W8  -> ESXTB
-                         _   -> panic "do_mul_may_oflo: impossible"
-            mul = case w of
-                    W32 -> SMULL
-                    W16 -> MUL
-                    W8  -> MUL
-                    _   -> panic "do_mul_may_oflo: impossible"
+        tmp1 <- getNewRegNat II32
+        tmp2 <- getNewRegNat II32
+        let extend dst arg =
+              case w of
+                W16 -> SXTH (OpReg W32 dst) (OpReg W32 arg)
+                W8  -> SXTB (OpReg W32 dst) (OpReg W32 arg)
+                _   -> panic "unreachable"
+            cmp_ext_mode =
+              case w of
+                W16 -> EUXTH
+                W8  -> EUXTB
+                _   -> panic "unreachable"
+            width = widthInBits w
+            opInt = OpImm . ImmInt
+
         return $ Any (intFormat w) (\dst ->
             code_x `appOL`
             code_y `snocOL`
-            mul (OpReg tmp_w tmp) (OpReg w reg_x) (OpReg w reg_y) `snocOL`
-            CMP (OpReg tmp_w tmp) (OpRegExt tmp_w tmp ext_mode 0) `snocOL`
+            extend tmp1 reg_x `snocOL`
+            extend tmp2 reg_y `snocOL`
+            MUL (OpReg W32 tmp1) (OpReg W32 tmp1) (OpReg W32 tmp2) `snocOL`
+            SBFX (OpReg W64 tmp2) (OpReg W64 tmp1) (opInt $ width - 1) (opInt 1) `snocOL`
+            UBFX (OpReg W32 tmp1) (OpReg W32 tmp1) (opInt width) (opInt width) `snocOL`
+            CMP (OpReg W32 tmp1) (OpRegExt W32 tmp2 cmp_ext_mode 0) `snocOL`
             CSET (OpReg w dst) NE)
 
 -- | Is a given number encodable as a bitmask immediate?


=====================================
testsuite/tests/codeGen/should_run/all.T
=====================================
@@ -233,7 +233,10 @@ test('OrigThunkInfo', normal, compile_and_run, ['-forig-thunk-info'])
 test('MulMayOflo_full',
      [ extra_files(['MulMayOflo.hs']),
        when(unregisterised(), skip),
-       unless(arch('x86_64') or arch('i386'), skip),
+       unless(
+         arch('aarch64') or arch('x86_64') or arch('i386'),
+         expect_broken(23742)
+       ),
         ignore_stdout],
      multi_compile_and_run,
      ['MulMayOflo', [('MulMayOflo_full.cmm', '')], ''])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/0eb54c050e46f447224167166dd6d2805ca8cdf5...824092f28f52d32b6ea3cd26e1e576524ee24969

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/0eb54c050e46f447224167166dd6d2805ca8cdf5...824092f28f52d32b6ea3cd26e1e576524ee24969
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