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riscv-gcc-1
Commit c0a08574 by Richard Kenner
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(expand_mult): Preserve useful sub-expressions when 

expanding a synthesized mult.

From-SVN: r6287
parent cfc327a2
Showing with 15 additions and 10 deletions
gcc/expmed.c
......@@ -2153,9 +2153,11 @@ expand_mult (mode, op0, op1, target, unsignedp)
for (opno = 1; opno < alg.ops; opno++)
{
int log = alg.log[opno];
rtx shift_subtarget = preserve_subexpressions_p () ? 0 : accum;
int preserve = preserve_subexpressions_p ();
rtx shift_subtarget = preserve ? 0 : accum;
rtx add_target = opno == alg.ops - 1 && target != 0 ? target : 0;
rtx accum_target = preserve ? 0 : accum;
switch (alg.op[opno])
{
case alg_shift:
......@@ -2168,7 +2170,7 @@ expand_mult (mode, op0, op1, target, unsignedp)
tem = expand_shift (LSHIFT_EXPR, mode, op0,
build_int_2 (log, 0), NULL_RTX, 0);
accum = force_operand (gen_rtx (PLUS, mode, accum, tem),
add_target ? add_target : accum);
add_target ? add_target : accum_target);
val_so_far += (HOST_WIDE_INT) 1 << log;
break;
......@@ -2176,23 +2178,25 @@ expand_mult (mode, op0, op1, target, unsignedp)
tem = expand_shift (LSHIFT_EXPR, mode, op0,
build_int_2 (log, 0), NULL_RTX, 0);
accum = force_operand (gen_rtx (MINUS, mode, accum, tem),
add_target ? add_target : accum);
add_target ? add_target : accum_target);
val_so_far -= (HOST_WIDE_INT) 1 << log;
break;
case alg_add_t2_m:
accum = expand_shift (LSHIFT_EXPR, mode, accum,
build_int_2 (log, 0), accum, 0);
build_int_2 (log, 0), shift_subtarget,
0);
accum = force_operand (gen_rtx (PLUS, mode, accum, op0),
add_target ? add_target : accum);
add_target ? add_target : accum_target);
val_so_far = (val_so_far << log) + 1;
break;
case alg_sub_t2_m:
accum = expand_shift (LSHIFT_EXPR, mode, accum,
build_int_2 (log, 0), accum, 0);
build_int_2 (log, 0), shift_subtarget,
0);
accum = force_operand (gen_rtx (MINUS, mode, accum, op0),
add_target ? add_target : accum);
add_target ? add_target : accum_target);
val_so_far = (val_so_far << log) - 1;
break;
......@@ -2200,7 +2204,7 @@ expand_mult (mode, op0, op1, target, unsignedp)
tem = expand_shift (LSHIFT_EXPR, mode, accum,
build_int_2 (log, 0), NULL_RTX, 0);
accum = force_operand (gen_rtx (PLUS, mode, accum, tem),
add_target ? add_target : accum);
add_target ? add_target : accum_target);
val_so_far += val_so_far << log;
break;
......@@ -2208,7 +2212,8 @@ expand_mult (mode, op0, op1, target, unsignedp)
tem = expand_shift (LSHIFT_EXPR, mode, accum,
build_int_2 (log, 0), NULL_RTX, 0);
accum = force_operand (gen_rtx (MINUS, mode, tem, accum),
add_target ? add_target : tem);
(add_target ? add_target
: preserve ? 0 : tem));
val_so_far = (val_so_far << log) - val_so_far;
break;
......
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