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  1. 01 Oct, 2015 5 commits
    • Subzero. Adds ldrex, strex, and dmb support (ARM32) · 16991847
      John Porto authored 
      These instructions are used to load/store data atomically, and to
notify the processor about a data memory barrier. They are used for
implementing the llvm.nacl.atomic.* lowerings.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1378303003 .
    • Add include files so that IceCompilerServer.cpp can compile on MSC. · 166cbf4a
      Karl Schimpf authored 
      A recent change to IceCompilerServer.cpp was added to allow fatal
errors to return exit status zero. However, this code called ::write
(a C function) that is not defined when compiling with MSC. This CL
adds includes to fix this problem.

BUG=None
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1379613005 .
    • Subzero: Fix a bug in register allocator overlap computation. · 48e3ae5c
      Jim Stichnoth authored 
      When the register allocator decides whether to allow the candidate's live range to overlap its preferred variable's live range (and share their register), it needs to consider whether any redefinitions in one variable occur within the live range of the other variable, in which case overlap should not be allowed.

There was a bug in the API for iterating over the defining instructions for a variable, in which the earliest definition might be ignored in some cases.  This came from the fact that the first definition and latter definitions are split apart for translation speed reasons, and a particular API is needed for finding an unambiguous first definition, which is possible when all definitions are within a single block but not so possible when definitions cross block boundaries.  (This only happens for the simple phi lowering.)

Since both semantics are needed, a separate API is added to support both.

For spec2k, the asm output is identical to before, so this changes nothing.  When translating spec2k with "-O2 -phi-edge-split=0", there is a single minor difference in ammp that actually looks legit in both cases.

However, when testing an upcoming CL, -phi-edge-split=0 triggered the bug, causing gcc and crafty to fail with incorrect output.

This CL also fixes some minor issues, and adds dump output of the instruction definition list when available.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1381563004 .
    • Subzero: Add missing content to CfgLocalAllocator. · 91d1b80f
      Jim Stichnoth authored 
      The std::list<> implementation used by g++ needs some extra stuff defined in the custom allocator.

This can be smoke-tested with:

  make -f Makefile.standalone CXX=g++ LLVM_EXTRA_WARNINGS="-Wno-unknown-pragmas -Wno-unused-parameter -Wno-comment -Wno-enum-compare -Wno-strict-aliasing" STDLIB_FLAGS=

until the link fails for unrelated reasons.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4325
R=kschimpf@google.com

Review URL: https://codereview.chromium.org/1367403004 .
    • Subzero: Change -asm-verbose output to print more useful info. · 238b4c16
      Jim Stichnoth authored 
      Frame offsets for variables are emitted using a symbolic name based on the variable's name.  This makes it a bit easier to digest the asm code.

For example, if variable Foo gets an esp offset 24, asm like this:
  ... 24(%esp) ...
will instead be emitted like this:
  lv$Foo = 24
  ...
  ... lv$Foo(%esp) ...

Predecessor labels are printed for each basic block.

Loop nest depth is printed for each basic block.  (Would be nice if we had loop header info as well.)

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1377323002 .
  3. 30 Sep, 2015 2 commits
  5. 28 Sep, 2015 2 commits
  7. 26 Sep, 2015 1 commit
    • Subzero: Improve usability of liveness-related tools. · 230d4101
      Jim Stichnoth authored 
      1. Rename all identifiers containing "nonkillable" to use the more understandable "redefined".

2. Change inferTwoAddress() to be called inferRedefinition(), and to check *all* instruction source variables (instead of just the first source operand) against the Dest variable.  This eliminates the need for several instances of _set_dest_redefined().  The performance impact on translation time is something like 0.1%, which is dwarfed by the usability gain.

3. Change a cryptic assert in (O2) live range construction to print detailed information on the liveness errors.

4. Change a cryptic assert in (Om1) live range construction to do the same.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1368993004 .
  9. 25 Sep, 2015 1 commit
  11. 24 Sep, 2015 1 commit
  13. 23 Sep, 2015 2 commits
    • Subzero: Improve handling of alloca instructions of constant size. · 55f931f6
      Jim Stichnoth authored 
      PNaCl simplifies varargs calls by creating a known-size argument array with an alloca instruction, and passing the address of that argument array.  These alloca instructions don't necessarily require use of a frame pointer, freeing up the frame pointer register for normal register allocation.

These varargs calls sometimes show up in cold paths of hot functions, so increasing the number of registers available to the register allocator can produce tangible gains.

This patch does a simple recognition of these alloca patterns, and on x86 doesn't force a frame pointer if all alloca instructions are suitable.

Future work is to avoid saving the alloca result as a local variable, and instead rematerialize the address as needed with respect to the stack or frame pointer.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1361803002 .
    • Subzero: Enable the asm-verbose.ll test for ARM32. · 467a222f
      Jim Stichnoth authored 
      BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1356953003 .
  15. 22 Sep, 2015 4 commits
  17. 21 Sep, 2015 1 commit
  19. 18 Sep, 2015 6 commits
  21. 17 Sep, 2015 2 commits
  23. 16 Sep, 2015 7 commits
  25. 15 Sep, 2015 4 commits
    • Subzero: Add a flag to mock up bounds checking on unsafe references. · ad2989b6
      Jim Stichnoth authored 
      The idea is that, before each load or store operation, we add a couple of compares/branches against the load/store address, one for the lower bound and one for the upper bound.  The conditional branches would be to an error throwing routine, and would never be taken in practice.  The compares might be against an immediate or a global location.  So a load of [reg] will mock-expand to this:

  cmp reg, 0
  je label
  cmp reg, 1
  je label
label:
  mov xxx, [reg]

We also make address mode inference less aggressive, because for a load of e.g. [eax+4*ecx], we can't compare that address expression against anything in any instruction, so we would have to reconstruct the address and undo at least part of the address mode inference.

The bounds-check mock is added for loads, stores, and rmw operations (with an exclusion for stores to the stack for out-arg pushes).  There are probably a small handful of other cases that are missing the bounds check, but if we add the transformation inside legalize(), which is the most obvious place, we may add extra bounds checks because sometimes legalize() is called twice on the same operand.

BUG= none
R=ascull@google.com

Review URL: https://codereview.chromium.org/1338633005 .
    • Subzero: Fix off-by-one asserts in intrinsic info lookup routines. · 92b31446
      Jim Stichnoth authored 
      It turns out that getNumArgs() and getReturnType() were never actually called except to print errors, so this bug was never encountered until now.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4315
R=ascull@google.com

Review URL: https://codereview.chromium.org/1347683002 .
    • Subzero: Fix labels for block profiling. · e7dbc0bc
      Jim Stichnoth authored 
      The problem is that the block profiling pass runs at the very beginning and commits to particular label strings, but the actual label names might change by emission time because of node reordering.

There was actually something of a workaround - given a label string from the profile output, inspect the *profiled* asm code and search for the block containing the increment of the counter location, as the name of the counter location label is related to the label string in the profile output.  However, it's tedious to mentally filter out the counter update code, and the counter update code has a huge impact on register allocation.

The solution is to use a persistent number in CfgNode for constructing the label string, which doesn't change when the nodes are reordered.

One note (independent of this change): Without block profiling, empty basic blocks are deleted and don't appear in the asm output.  But with block profiling, these blocks are never empty because they contain profile update instructions.  This means the profile output may contain labels that don't exist in the non-profiled asm.

Another note: New nodes created as a result of edge splitting from advanced phi lowering are not profiled.

BUG= none
R=ascull@google.com, jpp@chromium.org

Review URL: https://codereview.chromium.org/1341613002 .
    • Subzero: Don't contract an empty node that branches to itself. · 1921fba6
      Jim Stichnoth authored 
      BUG= https://code.google.com/p/nativeclient/issues/detail?id=4307
R=ascull@google.com

Review URL: https://codereview.chromium.org/1337113008 .
  27. 14 Sep, 2015 2 commits