Mercurial > hg > truffle
comparison src/cpu/x86/vm/x86_32.ad @ 3345:bad7ecd0b6ed
5091921: Sign flip issues in loop optimizer
Summary: Fix integer overflow problem in the code generated by loop optimizer.
Reviewed-by: never
| author | kvn |
|---|---|
| date | Wed, 04 May 2011 13:12:42 -0700 |
| parents | 15c9a0e16269 |
| children | 3d42f82cd811 |
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| 3344:0139aac70fb5 | 3345:bad7ecd0b6ed |
|---|---|
| 12983 ins_cost(300); | 12983 ins_cost(300); |
| 12984 | 12984 |
| 12985 format %{ "MAX $dst,$src" %} | 12985 format %{ "MAX $dst,$src" %} |
| 12986 opcode(0xCC); | 12986 opcode(0xCC); |
| 12987 ins_encode( max_enc(dst,src) ); | 12987 ins_encode( max_enc(dst,src) ); |
| 12988 ins_pipe( pipe_slow ); | |
| 12989 %} | |
| 12990 | |
| 12991 // ============================================================================ | |
| 12992 // Counted Loop limit node which represents exact final iterator value. | |
| 12993 // Note: the resulting value should fit into integer range since | |
| 12994 // counted loops have limit check on overflow. | |
| 12995 instruct loopLimit_eReg(eAXRegI limit, nadxRegI init, immI stride, eDXRegI limit_hi, nadxRegI tmp, eFlagsReg flags) %{ | |
| 12996 match(Set limit (LoopLimit (Binary init limit) stride)); | |
| 12997 effect(TEMP limit_hi, TEMP tmp, KILL flags); | |
| 12998 ins_cost(300); | |
| 12999 | |
| 13000 format %{ "loopLimit $init,$limit,$stride # $limit = $init + $stride *( $limit - $init + $stride -1)/ $stride, kills $limit_hi" %} | |
| 13001 ins_encode %{ | |
| 13002 int strd = (int)$stride$$constant; | |
| 13003 assert(strd != 1 && strd != -1, "sanity"); | |
| 13004 int m1 = (strd > 0) ? 1 : -1; | |
| 13005 // Convert limit to long (EAX:EDX) | |
| 13006 __ cdql(); | |
| 13007 // Convert init to long (init:tmp) | |
| 13008 __ movl($tmp$$Register, $init$$Register); | |
| 13009 __ sarl($tmp$$Register, 31); | |
| 13010 // $limit - $init | |
| 13011 __ subl($limit$$Register, $init$$Register); | |
| 13012 __ sbbl($limit_hi$$Register, $tmp$$Register); | |
| 13013 // + ($stride - 1) | |
| 13014 if (strd > 0) { | |
| 13015 __ addl($limit$$Register, (strd - 1)); | |
| 13016 __ adcl($limit_hi$$Register, 0); | |
| 13017 __ movl($tmp$$Register, strd); | |
| 13018 } else { | |
| 13019 __ addl($limit$$Register, (strd + 1)); | |
| 13020 __ adcl($limit_hi$$Register, -1); | |
| 13021 __ lneg($limit_hi$$Register, $limit$$Register); | |
| 13022 __ movl($tmp$$Register, -strd); | |
| 13023 } | |
| 13024 // signed devision: (EAX:EDX) / pos_stride | |
| 13025 __ idivl($tmp$$Register); | |
| 13026 if (strd < 0) { | |
| 13027 // restore sign | |
| 13028 __ negl($tmp$$Register); | |
| 13029 } | |
| 13030 // (EAX) * stride | |
| 13031 __ mull($tmp$$Register); | |
| 13032 // + init (ignore upper bits) | |
| 13033 __ addl($limit$$Register, $init$$Register); | |
| 13034 %} | |
| 12988 ins_pipe( pipe_slow ); | 13035 ins_pipe( pipe_slow ); |
| 12989 %} | 13036 %} |
| 12990 | 13037 |
| 12991 // ============================================================================ | 13038 // ============================================================================ |
| 12992 // Branch Instructions | 13039 // Branch Instructions |