commit 3386ebade2d28fd3ef68c576bb0375bd226a1320
author David Srbecky <dsrbecky@google.com> Wed Mar 14 21:30:25 2018 +0000
committer Christopher Ferris <cferris@google.com> Thu Mar 29 14:47:13 2018 +0000
tree 53f2e511a1e7b507239ab5c89cce0c50df474636
parent 324e27d284ef5061746a79ae22ed608460c985e9

Cache DWARF location rules for a given pc.

Decoding the DWARF opcodes is expensive so make sure we cache it.

This speeds unwinding in simpleperf by over a factor of 3x.

Add unit tests for this new behavior.

Bug: 77258731

Test: libbacktrace/libunwindstack unit tests on host and target.
Test: Ran debuggerd -b on various processes on target.
Change-Id: Ia516c0fa5d3e5f76746190bb4b6fdf49fd1c9388

libunwindstack/tests/DwarfSectionImplTest.cpp

diff --git a/libunwindstack/tests/DwarfSectionImplTest.cpp b/libunwindstack/tests/DwarfSectionImplTest.cpp
index c85764c..c340291 100644
--- a/libunwindstack/tests/DwarfSectionImplTest.cpp
+++ b/libunwindstack/tests/DwarfSectionImplTest.cpp
@@ -853,7 +853,8 @@
   fde.cfa_instructions_offset = 0x6000;
   fde.cfa_instructions_end = 0x6002;
 
-  dwarf_loc_regs_t cie_loc_regs{{6, {DWARF_LOCATION_REGISTER, {4, 0}}}};
+  dwarf_loc_regs_t cie_loc_regs;
+  cie_loc_regs[6] = DwarfLocation{DWARF_LOCATION_REGISTER, {4, 0}};
   this->section_->TestSetCachedCieLocRegs(0x8000, cie_loc_regs);
   this->memory_.SetMemory(0x6000, std::vector<uint8_t>{0x09, 0x04, 0x03});