[commit: ghc] ghc-7.10: UNREG: fix pprHexVal to emit zeros (#10518) (fa942e6)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : ghc-7.10
Link       : http://ghc.haskell.org/trac/ghc/changeset/fa942e67727c7bb06199055d16d3ae16642181e7/ghc

>---------------------------------------------------------------

commit fa942e67727c7bb06199055d16d3ae16642181e7
Author: Sergei Trofimovich <slyfox at gentoo.org>
Date:   Sun Jun 14 16:42:03 2015 +0100

    UNREG: fix pprHexVal to emit zeros (#10518)
    
    jakzale on #ghc reported a build failure
    when ported GHC on a new target.
    
    The code 'pprHexVal (2^32) W32' emits '0xU'
    which is invalid C.
    
    I've introduced bug in
        43f1b2ecd1960fa7377cf55a2b97c66059a701ef
    when added literal truncation. That truncation
    is a new source of zeros.
    
    Signed-off-by: Sergei Trofimovich <siarheit at google.com>
    
    Test Plan: added test and tested on UNREG ghc
    
    Reviewers: austin
    
    Reviewed By: austin
    
    Subscribers: thomie, bgamari
    
    Differential Revision: https://phabricator.haskell.org/D987
    
    GHC Trac Issues: #10518
    
    (cherry picked from commit a5084557b0b30faf3f89386ee6ee5a308dae51b1)


>---------------------------------------------------------------

fa942e67727c7bb06199055d16d3ae16642181e7
 compiler/cmm/PprC.hs                              | 5 +++--
 testsuite/tests/codeGen/should_compile/T10518.cmm | 5 +++++
 testsuite/tests/codeGen/should_compile/all.T      | 1 +
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/compiler/cmm/PprC.hs b/compiler/cmm/PprC.hs
index a2c3abf..3c4c379 100644
--- a/compiler/cmm/PprC.hs
+++ b/compiler/cmm/PprC.hs
@@ -1219,7 +1219,6 @@ commafy xs = hsep $ punctuate comma xs
 
 -- Print in C hex format: 0x13fa
 pprHexVal :: Integer -> Width -> SDoc
-pprHexVal 0 _ = ptext (sLit "0x0")
 pprHexVal w rep
   | w < 0     = parens (char '-' <>
                     ptext (sLit "0x") <> intToDoc (-w) <> repsuffix rep)
@@ -1239,7 +1238,9 @@ pprHexVal w rep
       repsuffix _ = char 'U'
 
       intToDoc :: Integer -> SDoc
-      intToDoc i = go (truncInt i)
+      intToDoc i = case truncInt i of
+                       0 -> char '0'
+                       v -> go v
 
       -- We need to truncate value as Cmm backend does not drop
       -- redundant bits to ease handling of negative values.
diff --git a/testsuite/tests/codeGen/should_compile/T10518.cmm b/testsuite/tests/codeGen/should_compile/T10518.cmm
new file mode 100644
index 0000000..966cd4a
--- /dev/null
+++ b/testsuite/tests/codeGen/should_compile/T10518.cmm
@@ -0,0 +1,5 @@
+foo() {
+    bits64 a;
+    a = 0x10000000000000000; // overflows 64 bits
+    return (a);
+}
diff --git a/testsuite/tests/codeGen/should_compile/all.T b/testsuite/tests/codeGen/should_compile/all.T
index e06cead..c78f9ac 100644
--- a/testsuite/tests/codeGen/should_compile/all.T
+++ b/testsuite/tests/codeGen/should_compile/all.T
@@ -30,3 +30,4 @@ test('debug', extra_clean(['debug.cmm']),
      run_command,
      ['$MAKE -s --no-print-directory debug'])
 test('T9964', normal, compile, ['-O'])
+test('T10518', [cmm_src], compile, [''])