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From: "pkoning at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/48990] New: MIPS wrong code error with -O1
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48990

           Summary: MIPS wrong code error with -O1
           Product: gcc
           Version: 4.5.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: pkoning@gcc.gnu.org


Created attachment 24241
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24241
preprocessed file (trimmed a bit) that reproduces the bug

The attached file compiles wrong code with -march=xlr -msoft-float -mabi=n32
-O1.  It compiles correctly with -O2.

The error shows up in basic block 3: the branch (beql $2,$0,$L10) has a li
$4,32 in its delay slot.  That clobbers $4 (A0) in the no-branch case, and A0
is still needed a few lines below.

The bug is also present in GCC 4.5.1

In looking at the debug dumps, I see the problem introduced in the "mach" pass
-- that pass builds a sequence insn for the branch and the load.

I'll try 4.6.0 next.