patches/gcc/3.3.2/empty6.patch
author "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
Sun May 20 13:48:26 2007 +0000 (2007-05-20)
changeset 112 ea15433daba0
permissions -rw-r--r--
Ah! I finally have a progress bar that doesn't stall the build!
- pipe size in Linux is only 8*512=4096 bytes
- pipe size is not setable
- when the feeding process spits out data faster than the eating
process can read it, then the feeding process stalls after 4KiB
of data sent to the pipe
- for us, the progress bar would spawn a sub-shell every line,
and the sub-shell would in turn spawn a 'date' command.
Which was sloooww as hell, and would cause some kind of a
starvation: the pipe was full most of the time, and the
feeding process was stalled all this time.

Now, we use internal variables and a little hack based onan offset
to determine the elapsed time. Much faster this way, but still
CPU-intensive.
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From 3.4 branch.  Fixes test failure
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FAIL: g++.dg/abi/empty6.C  (test for warnings, line 6)
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===================================================================
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RCS file: /cvs/gcc/gcc/gcc/testsuite/g++.dg/abi/empty6.C,v
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retrieving revision 1.1
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retrieving revision 1.2
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diff -u -r1.1 -r1.2
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--- gcc/gcc/testsuite/g++.dg/abi/empty6.C	2002/09/25 19:07:35	1.1
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+++ gcc/gcc/testsuite/g++.dg/abi/empty6.C	2003/06/03 19:10:09	1.2
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@@ -5,4 +5,9 @@
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 struct B {
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   A a; // { dg-warning "empty" }
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   virtual void f () {}
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-};
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+} __attribute__((aligned(8)));
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+/* The preceding attribute is necessary on targets with
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+   BIGGEST_ALIGNMENT <= 32 to trigger the warning, as otherwise a 32 bit
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+   offset is split into DECL_FIELD_OFFSET 4 and DECL_FIELD_BIT_OFFSET 0,
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+   and then there is no discrepancy between DECL_FIELD_OFFSET and
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+   byte_position to warn about.  */