Mercurial > hg > truffle
diff src/share/vm/opto/lcm.cpp @ 14456:abec000618bf
Merge
author | kvn |
---|---|
date | Tue, 28 Jan 2014 12:25:34 -0800 |
parents | de6a9e811145 b0133e4187d3 |
children | cd5d10655495 62c54fcc0a35 |
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--- a/src/share/vm/opto/lcm.cpp Tue Jan 28 11:21:43 2014 -0800 +++ b/src/share/vm/opto/lcm.cpp Tue Jan 28 12:25:34 2014 -0800 @@ -45,12 +45,52 @@ #ifdef TARGET_ARCH_MODEL_arm # include "adfiles/ad_arm.hpp" #endif -#ifdef TARGET_ARCH_MODEL_ppc -# include "adfiles/ad_ppc.hpp" +#ifdef TARGET_ARCH_MODEL_ppc_32 +# include "adfiles/ad_ppc_32.hpp" +#endif +#ifdef TARGET_ARCH_MODEL_ppc_64 +# include "adfiles/ad_ppc_64.hpp" #endif // Optimization - Graph Style +// Check whether val is not-null-decoded compressed oop, +// i.e. will grab into the base of the heap if it represents NULL. +static bool accesses_heap_base_zone(Node *val) { + if (Universe::narrow_oop_base() > 0) { // Implies UseCompressedOops. + if (val && val->is_Mach()) { + if (val->as_Mach()->ideal_Opcode() == Op_DecodeN) { + // This assumes all Decodes with TypePtr::NotNull are matched to nodes that + // decode NULL to point to the heap base (Decode_NN). + if (val->bottom_type()->is_oopptr()->ptr() == TypePtr::NotNull) { + return true; + } + } + // Must recognize load operation with Decode matched in memory operand. + // We should not reach here exept for PPC/AIX, as os::zero_page_read_protected() + // returns true everywhere else. On PPC, no such memory operands + // exist, therefore we did not yet implement a check for such operands. + NOT_AIX(Unimplemented()); + } + } + return false; +} + +static bool needs_explicit_null_check_for_read(Node *val) { + // On some OSes (AIX) the page at address 0 is only write protected. + // If so, only Store operations will trap. + if (os::zero_page_read_protected()) { + return false; // Implicit null check will work. + } + // Also a read accessing the base of a heap-based compressed heap will trap. + if (accesses_heap_base_zone(val) && // Hits the base zone page. + Universe::narrow_oop_use_implicit_null_checks()) { // Base zone page is protected. + return false; + } + + return true; +} + //------------------------------implicit_null_check---------------------------- // Detect implicit-null-check opportunities. Basically, find NULL checks // with suitable memory ops nearby. Use the memory op to do the NULL check. @@ -206,6 +246,14 @@ } break; } + + // On some OSes (AIX) the page at address 0 is only write protected. + // If so, only Store operations will trap. + // But a read accessing the base of a heap-based compressed heap will trap. + if (!was_store && needs_explicit_null_check_for_read(val)) { + continue; + } + // check if the offset is not too high for implicit exception { intptr_t offset = 0;