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| author | klebinger.andreas@gmx.at <klebinger.andreas@gmx.at> | 2018-09-18 17:46:38 +0200 |
|---|---|---|
| committer | Krzysztof Gogolewski <krz.gogolewski@gmail.com> | 2018-09-18 19:05:56 +0200 |
| commit | 6bb9bc7d3c935dcb77e0700cce28de2c9df646df (patch) | |
| tree | 04a5d2e6466e626b3b60f83e62ffae418463678b /testsuite/tests/codeGen | |
| parent | ce3897ffd6e7c8b8f36b8e920168bac8c7f836ae (diff) | |
| download | haskell-6bb9bc7d3c935dcb77e0700cce28de2c9df646df.tar.gz | |
Invert FP conditions to eliminate the explicit NaN check.
Summary:
Optimisation: we don't have to test the parity flag if we
know the test has already excluded the unordered case: eg >
and >= test for a zero carry flag, which can only occur for
ordered operands.
By reversing comparisons we can avoid testing the parity
for < and <= as well. This works since:
* If any of the arguments is an NaN CF gets set. Resulting in a false result.
* Since this allows us to rule out NaN we can exchange the arguments and invert the
direction of the arrows.
Test Plan: ci/nofib
Reviewers: carter, bgamari, alpmestan
Reviewed By: alpmestan
Subscribers: alpmestan, simonpj, jmct, rwbarton, thomie
GHC Trac Issues: #15196
Differential Revision: https://phabricator.haskell.org/D4990
Diffstat (limited to 'testsuite/tests/codeGen')
4 files changed, 14 insertions, 0 deletions
diff --git a/testsuite/tests/codeGen/should_compile/Makefile b/testsuite/tests/codeGen/should_compile/Makefile index 82896adbba..c94c8b6f92 100644 --- a/testsuite/tests/codeGen/should_compile/Makefile +++ b/testsuite/tests/codeGen/should_compile/Makefile @@ -38,3 +38,6 @@ T14999: '$(TEST_HC)' $(TEST_HC_OPTS) -O2 -g -c T14999.cmm -o T14999.o gdb --batch -ex 'file T14999.o' -ex 'disassemble stg_catch_frame_info' --nx | tr -s '[[:blank:]\n]' readelf --debug-dump=frames-interp T14999.o | tr -s '[[:blank:]\n]' + +T15196: + '$(TEST_HC)' $(TEST_HC_OPTS) -c -O -ddump-asm T15196.hs | grep "jp " ; echo $$? diff --git a/testsuite/tests/codeGen/should_compile/T15196.hs b/testsuite/tests/codeGen/should_compile/T15196.hs new file mode 100644 index 0000000000..6df88d8432 --- /dev/null +++ b/testsuite/tests/codeGen/should_compile/T15196.hs @@ -0,0 +1,4 @@ +module M where + +f :: Double -> Double -> Bool +f x y = if x < y then True else False diff --git a/testsuite/tests/codeGen/should_compile/T15196.stdout b/testsuite/tests/codeGen/should_compile/T15196.stdout new file mode 100644 index 0000000000..56a6051ca2 --- /dev/null +++ b/testsuite/tests/codeGen/should_compile/T15196.stdout @@ -0,0 +1 @@ +1
\ No newline at end of file diff --git a/testsuite/tests/codeGen/should_compile/all.T b/testsuite/tests/codeGen/should_compile/all.T index 9118b6c23b..dd6931f235 100644 --- a/testsuite/tests/codeGen/should_compile/all.T +++ b/testsuite/tests/codeGen/should_compile/all.T @@ -43,3 +43,9 @@ test('T14999', unless(opsys('linux') and arch('x86_64') and have_gdb() and have_readelf(), skip)], run_command, ['$MAKE -s --no-print-directory T14999']) + +# Verify that we optimize away redundant jumps for unordered comparisons. +test('T15196', + [ unless(arch('x86_64'),skip), + only_ways('normal'), + ], run_command, ['$MAKE -s --no-print-directory T15196']) |