Bignum: fix powMod for gmp backend (#18515)

Also reenable integerPowMod test which had never been reenabled by
mistake.

7 files changed, 20 insertions, 13 deletions

diff --git a/libraries/ghc-bignum/src/GHC/Num/BigNat/GMP.hs b/libraries/ghc-bignum/src/GHC/Num/BigNat/GMP.hs
index cb1fe500d9..965b7c76ec 100644
--- a/libraries/ghc-bignum/src/GHC/Num/BigNat/GMP.hs
+++ b/libraries/ghc-bignum/src/GHC/Num/BigNat/GMP.hs
@@ -349,7 +349,8 @@ bignat_powmod
    -> State# RealWorld
    -> State# RealWorld
 bignat_powmod r b e m s =
-   ioVoid (integer_gmp_powm# r b (wordArraySize# b) e (wordArraySize# e) m (wordArraySize# m)) s
+   case ioInt# (integer_gmp_powm# r b (wordArraySize# b) e (wordArraySize# e) m (wordArraySize# m)) s of
+      (# s', n #) -> mwaSetSize# r (narrowGmpSize# n) s'
 
 
 ----------------------------------------------------------------------
diff --git a/testsuite/tests/lib/integer/all.T b/testsuite/tests/lib/integer/all.T
index 3364bea241..0e32d11981 100644
--- a/testsuite/tests/lib/integer/all.T
+++ b/testsuite/tests/lib/integer/all.T
@@ -5,11 +5,11 @@ test('integerConstantFolding', normal, makefile_test, ['integerConstantFolding']
 test('fromToInteger', [], makefile_test, ['fromToInteger'])
 test('IntegerConversionRules', [], makefile_test, ['IntegerConversionRules'])
 test('gcdInteger', normal, compile_and_run, [''])
+test('integerPowMod', [], compile_and_run, [''])
 
 # skip ghci as it doesn't support unboxed tuples
 test('integerImportExport', [omit_ways(['ghci'])], compile_and_run, [''])
 
 # Disable GMP only tests
 #test('integerGcdExt', [omit_ways(['ghci'])], compile_and_run, [''])
-#test('integerPowMod', [], compile_and_run, [''])
 #test('integerGmpInternals', [], compile_and_run, [''])
diff --git a/testsuite/tests/lib/integer/integerPowMod.hs b/testsuite/tests/lib/integer/integerPowMod.hs
index 97cdad65b2..497e96cbf9 100644
--- a/testsuite/tests/lib/integer/integerPowMod.hs
+++ b/testsuite/tests/lib/integer/integerPowMod.hs
@@ -7,19 +7,12 @@ import Control.Monad
 
 import GHC.Word
 import GHC.Base
-import qualified GHC.Integer.GMP.Internals as I
-
-powModSecInteger :: Integer -> Integer -> Integer -> Integer
-powModSecInteger = I.powModSecInteger
-
-powModInteger :: Integer -> Integer -> Integer -> Integer
-powModInteger = I.powModInteger
+import GHC.Natural
 
 main :: IO ()
 main = do
-    print $ powModInteger b e m
-    print $ powModInteger b e (m-1)
-    print $ powModSecInteger b e (m-1)
+    print $ powModNatural b e m
+    print $ powModNatural b e (m-1)
 
   where
     b = 2988348162058574136915891421498819466320163312926952423791023078876139
diff --git a/testsuite/tests/lib/integer/integerPowMod.stdout b/testsuite/tests/lib/integer/integerPowMod.stdout
index bf3dc2e28b..64a4c568ac 100644
--- a/testsuite/tests/lib/integer/integerPowMod.stdout
+++ b/testsuite/tests/lib/integer/integerPowMod.stdout
@@ -1,3 +1,2 @@
 1527229998585248450016808958343740453059
 682382427572745901624116300491295556924
-682382427572745901624116300491295556924
diff --git a/testsuite/tests/numeric/should_run/T18515.hs b/testsuite/tests/numeric/should_run/T18515.hs
new file mode 100644
index 0000000000..2c17afc825
--- /dev/null
+++ b/testsuite/tests/numeric/should_run/T18515.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE MagicHash #-}
+
+import GHC.Num.BigNat
+import GHC.Num.Integer
+
+main :: IO ()
+main =
+    let b = integerToBigNatClamp# 251943445928310882947152017889649234
+        e = integerToBigNatClamp# 503886891856621765894304035779298468
+        m = integerToBigNatClamp# 503886891856621765894304035779298469
+        r = integerFromBigNat# (bigNatPowMod b e m)
+     in print r
diff --git a/testsuite/tests/numeric/should_run/T18515.stdout b/testsuite/tests/numeric/should_run/T18515.stdout
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/testsuite/tests/numeric/should_run/T18515.stdout
@@ -0,0 +1 @@
+1
diff --git a/testsuite/tests/numeric/should_run/all.T b/testsuite/tests/numeric/should_run/all.T
index f8d6ea3d4d..3f3cb45dda 100644
--- a/testsuite/tests/numeric/should_run/all.T
+++ b/testsuite/tests/numeric/should_run/all.T
@@ -72,3 +72,4 @@ test('T17303', normal, compile_and_run, [''])
 test('T18359', normal, compile_and_run, [''])
 test('T18499', normal, compile_and_run, [''])
 test('T18509', normal, compile_and_run, [''])
+test('T18515', normal, compile_and_run, [''])