+++ Ian Lance Taylor [05/07/07 17:48 -0700]: > "Gregory B. Prokopski" <[EMAIL PROTECTED]> writes: > > > One of the operations I need to perform is to reorder basic blocks in a > > particular manner. This works fine for example on i386 and other that have > > HAS_LONG_COND_BRANCH, HAS_LONG_UNCOND_BRANCH set. However on platforms like > > PPC, after the reordering, some branches are trying to reach destinations > > beyond their reach and I get errors during the final assembly. > > The hot/cold block partitioning code, -freorder-blocks-and-partition, > faces a similar problem. How do they solve it?
They only care about the edges that cross hot/cold sections boundaries. In my case, for all I care, the code of whole function can be in the hot section. > > For each function that has basic blocks reordered for code-copying, > > Scan all the insn's, find all jumps, > > For each jump check its destination label, and > > 1. compute the distance between the jump and the label > > (if possible use insn_lengths[] form final.c, or build it yourself > > using get_attr_length()) > > 2. compare the distance with what can be reached using the Mode > > (GET_MODE_SIZE, exact_log2()) > > 3. if Mode won't reach the destination, create an extra BB with an > > unconditional or indirect jump to the label (like bb-reorder.c) > > and redirect the original jump to it. > > But you seem to be within a single function, so I don't understand why > you have any trouble at all. Why doesn't the shorten_branches pass > work for you? I reorder the basic blocks in passes.c, right after compute_alignmnets (). I added a call to shorten_branches(NULL_RTX) right after my BB reordering, but it didn't change a thing, and I am still getting as errors: libsablevm.s: Assembler messages: libsablevm.s:56077: Error: operand out of range (91824 not between -32768 and 32767) libsablevm.s:71896: Error: operand out of range (-38472 not between -32768 and 32767) libsablevm.s:97418: Error: operand out of range (-51652 not between -32768 and 32767) Almost a hundred of these. I would need a way to debug this problem, which means I'd like to detect this problem earlier, say, when I do the block reordering. I thought I could do it with the algorigthm I described above. G. -- Gregory B. Prokopski <[EMAIL PROTECTED]> Sable Research Group http://www.sable.mcgill.ca Montreal, Quebec, Canada
