Commit Graph

9 Commits

Author SHA1 Message Date
serge-sans-paille 4ab3041acb Revert "[NFC] remove explicit default value for strboolattr attribute in tests"
This reverts commit bda6e5bee0.

See https://lab.llvm.org/buildbot/#/builders/109/builds/15424 for instance
2021-05-24 19:43:40 +02:00
serge-sans-paille bda6e5bee0 [NFC] remove explicit default value for strboolattr attribute in tests
Since d6de1e1a71, no attributes is quivalent to
setting attribute to false.

This is a preliminary commit for https://reviews.llvm.org/D99080
2021-05-24 19:31:04 +02:00
Paul Robinson c161775dec [FastISel] Flush local value map on every instruction
Local values are constants or addresses that can't be folded into
the instruction that uses them. FastISel materializes these in a
"local value" area that always dominates the current insertion
point, to try to avoid materializing these values more than once
(per block).

https://reviews.llvm.org/D43093 added code to sink these local
value instructions to their first use, which has two beneficial
effects. One, it is likely to avoid some unnecessary spills and
reloads; two, it allows us to attach the debug location of the
user to the local value instruction. The latter effect can
improve the debugging experience for debuggers with a "set next
statement" feature, such as the Visual Studio debugger and PS4
debugger, because instructions to set up constants for a given
statement will be associated with the appropriate source line.

There are also some constants (primarily addresses) that could be
produced by no-op casts or GEP instructions; the main difference
from "local value" instructions is that these are values from
separate IR instructions, and therefore could have multiple users
across multiple basic blocks. D43093 avoided sinking these, even
though they were emitted to the same "local value" area as the
other instructions. The patch comment for D43093 states:

  Local values may also be used by no-op casts, which adds the
  register to the RegFixups table. Without reversing the RegFixups
  map direction, we don't have enough information to sink these
  instructions.

This patch undoes most of D43093, and instead flushes the local
value map after(*) every IR instruction, using that instruction's
debug location. This avoids sometimes incorrect locations used
previously, and emits instructions in a more natural order.

In addition, constants materialized due to PHI instructions are
not assigned a debug location immediately; instead, when the
local value map is flushed, if the first local value instruction
has no debug location, it is given the same location as the
first non-local-value-map instruction.  This prevents PHIs
from introducing unattributed instructions, which would either
be implicitly attributed to the location for the preceding IR
instruction, or given line 0 if they are at the beginning of
a machine basic block.  Neither of those consequences is good
for debugging.

This does mean materialized values are not re-used across IR
instruction boundaries; however, only about 5% of those values
were reused in an experimental self-build of clang.

(*) Actually, just prior to the next instruction. It seems like
it would be cleaner the other way, but I was having trouble
getting that to work.

This reapplies commits cf1c774d and dc35368c, and adds the
modification to PHI handling, which should avoid problems
with debugging under gdb.

Differential Revision: https://reviews.llvm.org/D91734
2021-01-11 08:32:36 -08:00
Eric Leese 8b8088ac6c [lld] Use -1 as tombstone value for discarded code ranges
Under existing behavior discarded functions are relocated to have the start pc
0. This causes problems when debugging as they typically overlap the first
function and lldb symbol resolution frequently chooses a discarded function
instead of the correct one. Using the value -1 or -2 (depending on which DWARF
section we are writing) is sufficient to prevent lldb from resolving to these
symbols.

Reviewed By: MaskRay, yurydelendik, sbc100

Differential Revision: https://reviews.llvm.org/D91803
2020-12-01 17:06:32 -08:00
David Blaikie 615f63e149 Revert "[FastISel] Flush local value map on ever instruction" and dependent patches
This reverts commit cf1c774d6a.

This change caused several regressions in the gdb test suite - at least
a sample of which was due to line zero instructions making breakpoints
un-lined. I think they're worth investigating/understanding more (&
possibly addressing) before moving forward with this change.

Revert "[FastISel] NFC: Clean up unnecessary bookkeeping"
This reverts commit 3fd39d3694.

Revert "[FastISel] NFC: Remove obsolete -fast-isel-sink-local-values option"
This reverts commit a474657e30.

Revert "Remove static function unused after cf1c774."
This reverts commit dc35368ccf.

Revert "[lldb] Fix TestThreadStepOut.py after "Flush local value map on every instruction""
This reverts commit 53a14a47ee.
2020-12-01 14:26:23 -08:00
Paul Robinson cf1c774d6a [FastISel] Flush local value map on ever instruction
Local values are constants or addresses that can't be folded into
the instruction that uses them. FastISel materializes these in a
"local value" area that always dominates the current insertion
point, to try to avoid materializing these values more than once
(per block).

https://reviews.llvm.org/D43093 added code to sink these local
value instructions to their first use, which has two beneficial
effects. One, it is likely to avoid some unnecessary spills and
reloads; two, it allows us to attach the debug location of the
user to the local value instruction. The latter effect can
improve the debugging experience for debuggers with a "set next
statement" feature, such as the Visual Studio debugger and PS4
debugger, because instructions to set up constants for a given
statement will be associated with the appropriate source line.

There are also some constants (primarily addresses) that could be
produced by no-op casts or GEP instructions; the main difference
from "local value" instructions is that these are values from
separate IR instructions, and therefore could have multiple users
across multiple basic blocks. D43093 avoided sinking these, even
though they were emitted to the same "local value" area as the
other instructions. The patch comment for D43093 states:

  Local values may also be used by no-op casts, which adds the
  register to the RegFixups table. Without reversing the RegFixups
  map direction, we don't have enough information to sink these
  instructions.

This patch undoes most of D43093, and instead flushes the local
value map after(*) every IR instruction, using that instruction's
debug location. This avoids sometimes incorrect locations used
previously, and emits instructions in a more natural order.

This does mean materialized values are not re-used across IR
instruction boundaries; however, only about 5% of those values
were reused in an experimental self-build of clang.

(*) Actually, just prior to the next instruction. It seems like
it would be cleaner the other way, but I was having trouble
getting that to work.

Differential Revision: https://reviews.llvm.org/D91734
2020-11-25 13:05:00 -05:00
Paolo Severini aff75e1a1f [lld][Wasm] Wasm-ld emits invalid .debug_ranges entries for non-live symbols
When the debug info contains a relocation against a dead symbol, wasm-ld
may emit spurious range-list terminator entries (entries with Start==0
and End==0). This change fixes this by emitting the WasmRelocation
Addend as End value for a non-live symbol.

Reviewed by: sbc100, dblaikie

Differential Revision: https://reviews.llvm.org/D74781
2020-03-26 14:26:31 -07:00
Fangrui Song a36ddf0aa9 Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351 2019-12-24 16:27:51 -08:00
Yury Delendik d66aabc6d7 [WebAssembly] Move .debug_line section address of dead function outside section range
Summary:
Currently we are pointing all debug information that refer removed function code
to the beginning of the code section (offset = 0). A debugger may want to
resolve code offset to the debug information, which will collide with offsets
of the live functions.

Moving offsets of dead functions outside code section range.

Reviewers: sbc100

Reviewed By: sbc100

Subscribers: dblaikie, ruiu, alexcrichton, dschuff, aprantl, jgravelle-google, aheejin, sunfish, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D49446

llvm-svn: 342930
2018-09-24 23:50:55 +00:00