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re PR driver/41179 (Documentation for "-fno-toplevel-reorder" is confusing (and wrong))

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2018-11-09  Sandra Loosemore  <sandra@codesourcery.com>

	PR driver/41179
	PR middle-end/65703

	gcc/
	* doc/invoke.texi (Optimize Options): Clarify default behavior
	for -fno-toplevel-reorder, -fno-defer-pop, and -fno-branch-count-reg.

From-SVN: r265993
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Sandra Loosemore 2018-11-09 15:45:06 -05:00 committed by Sandra Loosemore
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2 changed files with 20 additions and 15 deletions
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@ -1,3 +1,10 @@
2018-11-09 Sandra Loosemore <sandra@codesourcery.com>
PR driver/41179
PR middle-end/65703
* doc/invoke.texi (Optimize Options): Clarify default behavior
for -fno-toplevel-reorder, -fno-defer-pop, and -fno-branch-count-reg.
2018-11-09 Bernd Edlinger <bernd.edlinger@hotmail.de>
PR tree-optimization/87940

28
gcc/doc/invoke.texi
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@ -8062,12 +8062,11 @@ optimizations to be performed is desired.
@table @gcctabopt
@item -fno-defer-pop
@opindex fno-defer-pop
Always pop the arguments to each function call as soon as that function
returns. For machines that must pop arguments after a function call,
the compiler normally lets arguments accumulate on the stack for several
function calls and pops them all at once.
Disabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
For machines that must pop arguments after a function call, always pop
the arguments as soon as each function returns.
At levels @option{-O1} and higher, @option{-fdefer-pop} is the default;
this allows the compiler to let arguments accumulate on the stack for several
function calls and pop them all at once.
@item -fforward-propagate
@opindex fforward-propagate
@ -8284,18 +8283,16 @@ life-range analysis. This option is effective only with
@item -fno-branch-count-reg
@opindex fno-branch-count-reg
Avoid running a pass scanning for opportunities to use ``decrement and
branch'' instructions on a count register instead of generating sequences
of instructions that decrement a register, compare it against zero, and
Disable the optimization pass that scans for opportunities to use
``decrement and branch'' instructions on a count register instead of
instruction sequences that decrement a register, compare it against zero, and
then branch based upon the result. This option is only meaningful on
architectures that support such instructions, which include x86, PowerPC,
IA-64 and S/390. Note that the @option{-fno-branch-count-reg} option
doesn't remove the decrement and branch instructions from the generated
instruction stream introduced by other optimization passes.
Enabled by default at @option{-O1} and higher.
The default is @option{-fbranch-count-reg}.
The default is @option{-fbranch-count-reg} at @option{-O1} and higher.
@item -fno-function-cse
@opindex fno-function-cse
@ -9684,9 +9681,10 @@ are not removed. This option is intended to support existing code
that relies on a particular ordering. For new code, it is better to
use attributes when possible.
Enabled at level @option{-O0}. When disabled explicitly, it also implies
@option{-fno-section-anchors}, which is otherwise enabled at @option{-O0} on some
targets.
@option{-ftoplevel-reorder} is the default at @option{-O1} and higher, and
also at @option{-O0} if @option{-fsection-anchors} is explicitly requested.
Additionally @option{-fno-toplevel-reorder} implies
@option{-fno-section-anchors}.
@item -fweb
@opindex fweb