http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55186
Bug #: 55186
Summary: gcc.dg/const-uniq-1.c fails due to vector expected but
not being in the constant pool
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: testsuite
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: h...@gcc.gnu.org
Target: cris-axis-elf
Created attachment 28601
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28601
const-uniq-1.c.004t.gimple
While technically this is a regression, the reason for the brief PASS period is
likely related to a temporary severe bug in the source tree rather than the
more common sequence: a conscious change foiled by a later bug. This is a rare
event!
This test previously failed, started passing somewhere in the (]-range
193059:193061 (likely due to the bug in r193061) and started failing again
somewhere in the (]-range 193063:193070 (likely due to the bugfix in r193064).
At r193109, the const-uniq-1.c.004t.gimple dump is as attached: no label
present for the expected constant-pool entry.
The assembly output for the vector initializations are piecewise, one for each
element:
moveq 1,$r9
move.d $r9,[$sp+4]
The test assumes a single vector in the constant pool supposedly used with some
memcpy-equivalent (call or in-line expansion). At first glance, the piecewise
initialization might seem suboptimal, but a memcpy call would *not* be better
for -Os for this target, when counting the constant vector (well, twice).
Piecewise initialization would be optimal - if the storing instructions use
post-increment instead of indexing, as expected by the specified relevant
target macros. (N.B.: poor autoincdec generation is a long-standing flaw in
gcc covered by PRs elsewhere).
Constant-pool vectors and memcpy are optimal for e.g. vectors four times as
large; will propose such a patch for this test-case.
