Commit Graph

14 Commits

Author SHA1 Message Date
James Molloy 6215fad0e9 [ARM] Constant pool promotion - fix alignment calculation
Global variables are GlobalValues, so they have explicit alignment. Querying
DataLayout for the alignment was incorrect.

Testcase added.

llvm-svn: 283423
2016-10-06 07:56:00 +00:00
James Molloy 9abb2fa5bb [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

This recommit contains fixes for a nasty bug related to fast-isel fallback - because
fast-isel doesn't know about this optimization, if it runs and emits references to
a string that we inline (because fast-isel fell back to SDAG) we will end up
with an inlined string and also an out-of-line string, and we won't emit the
out-of-line string, causing backend failures.

It also contains fixes for emitting .text relocations which made the sanitizer
bots unhappy.

llvm-svn: 282387
2016-09-26 07:26:24 +00:00
James Molloy 85124c76fc Revert "[ARM] Promote small global constants to constant pools"
This reverts commit r282241. It caused http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/19882.

llvm-svn: 282249
2016-09-23 13:35:43 +00:00
James Molloy 1ce54d6be2 [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

This recommit contains fixes for a nasty bug related to fast-isel fallback - because
fast-isel doesn't know about this optimization, if it runs and emits references to
a string that we inline (because fast-isel fell back to SDAG) we will end up
with an inlined string and also an out-of-line string, and we won't emit the
out-of-line string, causing backend failures.

It also contains fixes for emitting .text relocations which made the sanitizer
bots unhappy.

llvm-svn: 282241
2016-09-23 12:15:58 +00:00
Nico Weber 903859c0e4 Revert r281715, it caused PR30475
llvm-svn: 282076
2016-09-21 15:33:24 +00:00
James Molloy 0dc4708fca [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

This recommit contains fixes for a nasty bug related to fast-isel fallback - because
fast-isel doesn't know about this optimization, if it runs and emits references to
a string that we inline (because fast-isel fell back to SDAG) we will end up
with an inlined string and also an out-of-line string, and we won't emit the
out-of-line string, causing backend failures.

It also contains fixes for emitting .text relocations which made the sanitizer
bots unhappy.

llvm-svn: 281715
2016-09-16 10:17:04 +00:00
Evgeniy Stepanov a0601a40f7 Revert "[ARM] Promote small global constants to constant pools"
This reverts r281604, which adds text relocations to ARM binaries.

llvm-svn: 281645
2016-09-15 19:13:32 +00:00
James Molloy fe7fd879d7 [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

This recommit contains fixes for a nasty bug related to fast-isel fallback - because
fast-isel doesn't know about this optimization, if it runs and emits references to
a string that we inline (because fast-isel fell back to SDAG) we will end up
with an inlined string and also an out-of-line string, and we won't emit the
out-of-line string, causing backend failures.

llvm-svn: 281604
2016-09-15 12:30:27 +00:00
Evgeniy Stepanov e97d3b90b9 Revert "[ARM] Promote small global constants to constant pools"
Breaks Android tests by introducing text relocations to ARM binaries.

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/25362/steps/run%20asan%20lit%20tests%20%5Barm%2Fbullhead-userdebug%2FMTC20F%5D/logs/stdio

llvm-svn: 281526
2016-09-14 20:02:30 +00:00
James Molloy 13065b00ba [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

llvm-svn: 281484
2016-09-14 14:47:27 +00:00
James Molloy 043d613791 Revert "[ARM] Promote small global constants to constant pools"
This reverts commit r281314. Speculatively revert as it's possible this caused linker errors: http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/19656

llvm-svn: 281327
2016-09-13 12:45:51 +00:00
James Molloy 3e4bc66134 [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

llvm-svn: 281314
2016-09-13 10:28:11 +00:00
James Molloy 3d06ff22b7 Revert "[ARM] Promote small global constants to constant pools"
This reverts commit r281213. It made a bot go bang: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15-full/builds/14625

llvm-svn: 281228
2016-09-12 16:18:23 +00:00
James Molloy 8f82d45ff4 [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

llvm-svn: 281213
2016-09-12 13:42:16 +00:00