Chris Lattner e0391beda8 Fix a FIXME: if we are inserting code for a PHI argument, split the critical ...

edge so that the code is not always executed for both operands.  This
prevents LSR from inserting code into loops whose exit blocks contain
PHI uses of IV expressions (which are outside of loops).  On gzip, for
example, we turn this ugly code:

.LBB_test_1:    ; loopentry
        add r27, r3, r28
        lhz r27, 3(r27)
        add r26, r4, r28
        lhz r26, 3(r26)
        add r25, r30, r28    ;; Only live if exiting the loop
        add r24, r29, r28    ;; Only live if exiting the loop
        cmpw cr0, r27, r26
        bne .LBB_test_5 ; loopexit

into this:

.LBB_test_1:    ; loopentry
        or r27, r28, r28
        add r28, r3, r27
        lhz r28, 3(r28)
        add r26, r4, r27
        lhz r26, 3(r26)
        cmpw cr0, r28, r26
        beq .LBB_test_3 ; shortcirc_next.0
.LBB_test_2:    ; loopentry.loopexit_crit_edge
        add r2, r30, r27
        add r8, r29, r27
        b .LBB_test_9   ; loopexit
.LBB_test_2:    ; shortcirc_next.0
        ...
        blt .LBB_test_1


into this:

.LBB_test_1:    ; loopentry
        or r27, r28, r28
        add r28, r3, r27
        lhz r28, 3(r28)
        add r26, r4, r27
        lhz r26, 3(r26)
        cmpw cr0, r28, r26
        beq .LBB_test_3 ; shortcirc_next.0
.LBB_test_2:    ; loopentry.loopexit_crit_edge
        add r2, r30, r27
        add r8, r29, r27
        b .LBB_t_3:    ; shortcirc_next.0
.LBB_test_3:    ; shortcirc_next.0
        ...
        blt .LBB_test_1


Next step: get the block out of the loop so that the loop is all
fall-throughs again.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22766 91177308-0d34-0410-b5e6-96231b3b80d8

2005-08-12 22:06:11 +00:00

..

ADCE.cpp

preserve calling conventions when hacking on code

2005-05-14 12:25:32 +00:00

BasicBlockPlacement.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

CondPropagate.cpp

Fix a fixme in CondPropagate.cpp by moving a PhiNode optimization into

2005-08-04 23:24:19 +00:00

ConstantProp.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

CorrelatedExprs.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

DCE.cpp

clean up and modernize this pass.

2005-05-08 18:45:26 +00:00

DeadStoreElimination.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

GCSE.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

IndVarSimplify.cpp

Allow indvar simplify to canonicalize ANY affine IV, not just affine IVs with

2005-08-10 01:12:06 +00:00

InstructionCombining.cpp

Use the new 'moveBefore' method to simplify some code. Really, which is

2005-08-08 19:11:57 +00:00

LICM.cpp

prevent va_arg from being hoisted from a loop

2005-06-20 13:36:33 +00:00

LoopStrengthReduce.cpp

Fix a FIXME: if we are inserting code for a PHI argument, split the critical

2005-08-12 22:06:11 +00:00

LoopUnroll.cpp

Eliminate tabs and trailing spaces

2005-04-23 21:38:35 +00:00

LoopUnswitch.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

LowerConstantExprs.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

LowerGC.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

LowerPacked.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

Makefile

…

PRE.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

Reassociate.cpp

Use the new 'moveBefore' method to simplify some code. Really, which is

2005-08-08 19:11:57 +00:00

ScalarReplAggregates.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

SCCP.cpp

Eliminate tabs and trailing spaces

2005-04-23 21:38:35 +00:00

SimplifyCFG.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

TailDuplication.cpp

Remove trailing whitespace

2005-04-21 23:48:37 +00:00

TailRecursionElimination.cpp

Use the new 'moveBefore' method to simplify some code. Really, which is

2005-08-08 19:11:57 +00:00