-
Summary: This diff is a part of the bigger project which goal is to improve common profiling tools support (perf) for GHC binaries. A similar job was already done and reverted in the past: * https://phabricator.haskell.org/rGHCb1f453e16f0ce11a2ab18cc4c350bdcbd36299a6 * https://phabricator.haskell.org/rGHCf1f3c4f50650110ad0f700d6566a44c515b0548f Reasoning: `Perf` and similar tools build in memory symbol table from the .symtab section of the ELF file to display human-readable function names instead of the addresses in the output. `Perf` uses only two types of symbols: `@function` and `@notype` but GHC is not capable to produce any `@function` symbols so the `perf` output is pretty useless (All the haskell symbols that you can see in `perf` now are `@notype` internal symbols extracted by mistake/hack). The changes: * mark code related symbols as @function * small hack to mark InfoTable symbols as code if TABLES_NEXT_TO_CODE is true Limitations: * The perf symbolization support is not complete after this patch but I'm working on the second patch. * Constructor symbols are not supported. To fix that we can issue extra local symbols which mark code sections as code and will be only used for debug. Test Plan: tests any additional ideas? Perf output on stock ghc 8.4.1: ``` 9.78% FibbSlow FibbSlow [.] ckY_info 9.59% FibbSlow FibbSlow [.] cjqd_info 7.17% FibbSlow FibbSlow [.] c3sg_info 6.62% FibbSlow FibbSlow [.] c1X_info 5.32% FibbSlow FibbSlow [.] cjsX_info 4.18% FibbSlow FibbSlow [.] s3rN_info 3.82% FibbSlow FibbSlow [.] c2m_info 3.68% FibbSlow FibbSlow [.] cjlJ_info 3.26% FibbSlow FibbSlow [.] c3sb_info 3.19% FibbSlow FibbSlow [.] cjPQ_info 3.05% FibbSlow FibbSlow [.] cjQd_info 2.97% FibbSlow FibbSlow [.] cjAB_info 2.78% FibbSlow FibbSlow [.] cjzP_info 2.40% FibbSlow FibbSlow [.] cjOS_info 2.38% FibbSlow FibbSlow [.] s3rK_info 2.27% FibbSlow FibbSlow [.] cjq0_info 2.18% FibbSlow FibbSlow [.] cKQ_info 2.13% FibbSlow FibbSlow [.] cjSl_info 1.99% FibbSlow FibbSlow [.] s3rL_info 1.98% FibbSlow FibbSlow [.] c2cC_info 1.80% FibbSlow FibbSlow [.] s3rO_info 1.37% FibbSlow FibbSlow [.] c2f2_info ... ``` Perf output on patched ghc: ``` 7.97% FibbSlow FibbSlow [.] c3rM_info 6.75% FibbSlow FibbSlow [.] 0x000000000032cfa8 6.63% FibbSlow FibbSlow [.] cifA_info 4.98% FibbSlow FibbSlow [.] integerzmgmp_GHCziIntegerziType_eqIntegerzh_info 4.55% FibbSlow FibbSlow [.] chXn_info 4.52% FibbSlow FibbSlow [.] c3rH_info 4.45% FibbSlow FibbSlow [.] chZB_info 4.04% FibbSlow FibbSlow [.] Main_fibbzuslow_info 4.03% FibbSlow FibbSlow [.] stg_ap_0_fast 3.76% FibbSlow FibbSlow [.] chXA_info 3.67% FibbSlow FibbSlow [.] cifu_info 3.25% FibbSlow FibbSlow [.] ci4r_info 2.64% FibbSlow FibbSlow [.] s3rf_info 2.42% FibbSlow FibbSlow [.] s3rg_info 2.39% FibbSlow FibbSlow [.] integerzmgmp_GHCziIntegerziType_eqInteger_info 2.25% FibbSlow FibbSlow [.] integerzmgmp_GHCziIntegerziType_minusInteger_info 2.17% FibbSlow FibbSlow [.] ghczmprim_GHCziClasses_zeze_info 2.09% FibbSlow FibbSlow [.] cicc_info 2.03% FibbSlow FibbSlow [.] 0x0000000000331e15 2.02% FibbSlow FibbSlow [.] s3ri_info 1.91% FibbSlow FibbSlow [.] 0x0000000000331bb8 1.89% FibbSlow FibbSlow [.] ci4N_info ... ``` Reviewers: simonmar, niteria, bgamari, goldfire Reviewed By: simonmar, bgamari Subscribers: lelf, rwbarton, thomie, carter GHC Trac Issues: #15501 Differential Revision: https://phabricator.haskell.org/D4713
c23f057f