From 87d62e4e7505c77c53ebc00d5bc56540863699db Mon Sep 17 00:00:00 2001 From: Alon Zakai Date: Thu, 17 Apr 2014 11:26:13 -0700 Subject: eliminate loop vars even if used after increment, by adding another helper (which has less overhead than the previous helper) --- tools/eliminator/asm-eliminator-test-output.js | 52 +++++++++++++++----------- tools/eliminator/asm-eliminator-test.js | 23 +++++++++++- tools/js-optimizer.js | 17 +++++++-- 3 files changed, 67 insertions(+), 25 deletions(-) (limited to 'tools') diff --git a/tools/eliminator/asm-eliminator-test-output.js b/tools/eliminator/asm-eliminator-test-output.js index 9caf99d0..1a5dca55 100644 --- a/tools/eliminator/asm-eliminator-test-output.js +++ b/tools/eliminator/asm-eliminator-test-output.js @@ -147,27 +147,25 @@ function looop3() { } } function looop4() { - var i = 0, helper = 0; + var i = 0, i$looptemp = 0; while (1) { do_it(); - helper = i + 1 | 0; - f(i, helper); - if (condition()) { - i = helper; - } else { + i$looptemp = i; + i = i + 1 | 0; + f(i$looptemp, i); + if (!condition()) { break; } } } function looop4b() { - var i = 0, helper = 0; + var i = 0, i$looptemp = 0; while (1) { do_it(); - helper = i + 1 | 0; - g(helper); - if (condition(i)) { - i = helper; - } else { + i$looptemp = i; + i = i + 1 | 0; + g(i); + if (!condition(i$looptemp)) { break; } } @@ -251,24 +249,22 @@ function multiloop($n_0, $35) { function multiloop2($n_0, $35) { $n_0 = $n_0 | 0; $35 = $35 | 0; - var $p_0 = 0, $39 = 0, $41 = 0, $46 = 0; + var $p_0 = 0, $41 = 0, $p_0$looptemp = 0; $n_0 = $35; $p_0 = (HEAP32[$15 >> 2] | 0) + ($35 << 1) | 0; while (1) { - $39 = $p_0 - 2 | 0; - $41 = HEAPU16[$39 >> 1] | 0; + $p_0$looptemp = $p_0; + $p_0 = $p_0 - 2 | 0; + $41 = HEAPU16[$p_0 >> 1] | 0; if ($41 >>> 0 < $2 >>> 0) { $_off0 = 0; } else { $_off0 = $41 - $2 & 65535; } - HEAP16[$39 >> 1] = $p_0; - $46 = $n_0 - 1 | 0; - if (($46 | 0) == 0) { + HEAP16[$p_0 >> 1] = $p_0$looptemp; + $n_0 = $n_0 - 1 | 0; + if (($n_0 | 0) == 0) { break; - } else { - $n_0 = $46; - $p_0 = $39; } } } @@ -901,4 +897,18 @@ function elimOneLoopVar4() { } } } +function elimOneLoopVarStillUsed() { + var $call10 = Math_fround(0), $curri$012 = 0, $j$010 = 0, $retval$0 = 0, $j$010$looptemp = 0; + while (1) { + $j$010$looptemp = $j$010; + $j$010 = $j$010 + 1 | 0; + if ((($curri$012 | 0) % ($j$010$looptemp | 0) & -1 | 0) == 0) { + break; + } + if (!(Math_fround($j$010 | 0) < $call10)) { + break; + } + } + return $retval$0 | 0; +} diff --git a/tools/eliminator/asm-eliminator-test.js b/tools/eliminator/asm-eliminator-test.js index a3de3d9d..d5bbd8d5 100644 --- a/tools/eliminator/asm-eliminator-test.js +++ b/tools/eliminator/asm-eliminator-test.js @@ -1131,5 +1131,26 @@ function elimOneLoopVar4() { } } } -// EMSCRIPTEN_GENERATED_FUNCTIONS: ["asm", "__Z11printResultPiS_j", "_segment_holding", "__ZN5identC2EiPKcPci", "_vec2Length", "exc", "label", "confuusion", "tempDouble", "_org_apache_harmony_luni_util_NumberConverter_freeFormat__", "__ZN23b2EdgeAndPolygonContact8EvaluateEP10b2ManifoldRK11b2TransformS4_", "_java_nio_charset_Charset_forNameInternal___java_lang_String", "looop2", "looop3", "looop4", "looop5", "looop6", "looop7", "looop8", "multiloop", "multiloop2", "tempDouble2", "watIf", "select2", "binary", "cute", "selfAssign", "elimOneLoopVar", "elimOneLoopVar2", "elimOneLoopVar3", "elimOneLoopVar4"] +function elimOneLoopVarStillUsed() { + var $0 = 0, $1 = 0, $arg$0 = 0, $arrayidx = 0, $call10 = Math_fround(0), $cmp = 0, $cmp11 = 0, $cmp119 = 0, $cmp12 = 0, $cmp7 = 0, $conv = 0, $conv8 = Math_fround(0), $conv9 = Math_fround(0), $curri$012 = 0, $inc = 0, $inc14$primes$0 = 0, $inc16 = 0, $j$010 = 0, $ok$0 = 0; + var $primes$011 = 0, $rem = 0, $retval$0 = 0, $sub = 0, $vararg_buffer1 = 0, label = 0, sp = 0; + while (1) { + $rem = ($curri$012 | 0) % ($j$010 | 0) & -1; + $cmp12 = ($rem | 0) == 0; + $inc = $j$010 + 1 | 0; + if ($cmp12) { + $ok$0 = 0; + break; + } + $conv8 = Math_fround($inc | 0); + $cmp11 = $conv8 < $call10; + if ($cmp11) { + $j$010 = $inc; + } else { + break; + } + } + return $retval$0 | 0; +} +// EMSCRIPTEN_GENERATED_FUNCTIONS: ["asm", "__Z11printResultPiS_j", "_segment_holding", "__ZN5identC2EiPKcPci", "_vec2Length", "exc", "label", "confuusion", "tempDouble", "_org_apache_harmony_luni_util_NumberConverter_freeFormat__", "__ZN23b2EdgeAndPolygonContact8EvaluateEP10b2ManifoldRK11b2TransformS4_", "_java_nio_charset_Charset_forNameInternal___java_lang_String", "looop2", "looop3", "looop4", "looop5", "looop6", "looop7", "looop8", "multiloop", "multiloop2", "tempDouble2", "watIf", "select2", "binary", "cute", "selfAssign", "elimOneLoopVar", "elimOneLoopVar2", "elimOneLoopVar3", "elimOneLoopVar4", "elimOneLoopVarStillUsed"] diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js index c4585b84..32c26c51 100644 --- a/tools/js-optimizer.js +++ b/tools/js-optimizer.js @@ -3519,12 +3519,15 @@ function eliminate(ast, memSafe) { seenUses[name]++; } } else if (type === 'while') { + if (!asm) return; // try to remove loop helper variables specifically var stats = node[2][1]; var last = stats[stats.length-1]; if (last && last[0] === 'if' && last[2][0] === 'block' && last[3] && last[3][0] === 'block') { var ifTrue = last[2]; var ifFalse = last[3]; + clearEmptyNodes(ifTrue[1]); + clearEmptyNodes(ifFalse[1]); var flip = false; if (ifFalse[1][0] && ifFalse[1][0][0] === 'break') { // canonicalize break in the if var temp = ifFalse; @@ -3589,17 +3592,25 @@ function eliminate(ast, memSafe) { } } if (found < 0) return; + // if a loop variable is used after we assigned to the helper, we must save its value and use that. + // (note that this can happen due to elimination, if we eliminate an expression containing the + // loop var far down, past the assignment!) + var temp = looper + '$looptemp'; var looperUsed = false; - for (var i = found+1; i < stats.length && !looperUsed; i++) { + assert(!(temp in asmData.vars)); + for (var i = found+1; i < stats.length; i++) { var curr = i < stats.length-1 ? stats[i] : last[1]; // on the last line, just look in the condition traverse(curr, function(node, type) { if (type === 'name' && node[1] === looper) { + node[1] = temp; looperUsed = true; - return true; } }); } - if (looperUsed) return; + if (looperUsed) { + asmData.vars[temp] = asmData.vars[looper]; + stats.splice(found, 0, ['stat', ['assign', true, ['name', temp], ['name', looper]]]); + } } for (var l = 0; l < helpers.length; l++) { for (var k = 0; k < helpers.length; k++) { -- cgit v1.2.3-18-g5258