#7192: Bug in -fregs-graph with -fnew-codegen
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Reporter: simonmar | Owner: benl
Type: bug | Status: new
Priority: highest | Milestone: 7.8.1
Component: Compiler | Version: 7.7
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking: 4258
Related: |
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Comment(by benl):
@simonmar: yes. It looks like the NCG (or something) is broken
independently from the graph allocator.
When compiling with -fllvm I get the right answer:
{{{
desire:diophantine benl$ pwd
/Users/benl/devel/ghc/ghc-head-devel/testsuite/tests/dph/diophantine
desire:diophantine benl$ /Users/benl/devel/ghc/ghc-head-devel/inplace/bin
/ghc-stage2 --version
The Glorious Glasgow Haskell Compilation System, version 7.7.20121112
desire:diophantine benl$ /Users/benl/devel/ghc/ghc-head-devel/inplace/bin
/ghc-stage2 \
-fforce-recomp -dcore-lint -dcmm-lint \
--make -o dph-diophantine-copy-fast Main \
-O -fno-enable-rewrite-rules -package dph-lifted-copy -fllvm
desire:diophantine benl$ ./dph-diophantine-copy-fast
(1260,[2,2,1,1,0])
(1260,[2,2,1,1,0])
(1260,fromList<PArray> [2,2,1,1,0])
}}}
But with with NCG `-fno-regs-graph` it gives a different answer:
{{{
desire:diophantine benl$ /Users/benl/devel/ghc/ghc-head-devel/inplace/bin
/ghc-stage2 \
-fforce-recomp -dcore-lint -dcmm-lint \
--make -o dph-diophantine-copy-fast Main \
-O -fno-enable-rewrite-rules -package dph-lifted-copy -fno-regs-graph
desire:diophantine benl$ ./dph-diophantine-copy-fast
dph-diophantine-copy-fast: Prelude.minimum: empty list
}}}
Compiling in different ways by typing `make` in that same directory
sometimes causes a stack overflow instead of `Prelude.minimum: empty list`
I looked through the output assembly code but didn't find code code
sequence in your initial report. My approach was to compile with `-ddump-
cmmz-sp -ddump-to-file` then grep
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7192#comment:6>
GHC <http://www.haskell.org/ghc/>
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