forked from OSchip/llvm-project
7f5866c227
This addresses PR26055 LiveDebugValues is very slow.
Contrary to the old LiveDebugVariables pass LiveDebugValues currently
doesn't look at the lexical scopes before inserting a DBG_VALUE
intrinsic. This means that we often propagate DBG_VALUEs much further
down than necessary. This is especially noticeable in large C++
functions with many inlined method calls that all use the same
"this"-pointer.
For example, in the following code it makes no sense to propagate the
inlined variable a from the first inlined call to f() into any of the
subsequent basic blocks, because the variable will always be out of
scope:
void sink(int a);
void __attribute((always_inline)) f(int a) { sink(a); }
void foo(int i) {
f(i);
if (i)
f(i);
f(i);
}
This patch reuses the LexicalScopes infrastructure we have for
LiveDebugVariables to take this into account.
The effect on compile time and memory consumption is quite noticeable:
I tested a benchmark that is a large C++ source with an enormous
amount of inlined "this"-pointers that would previously eat >24GiB
(most of them for DBG_VALUE intrinsics) and whose compile time was
dominated by LiveDebugValues. With this patch applied the memory
consumption is 1GiB and 1.7% of the time is spent in LiveDebugValues.
https://reviews.llvm.org/D24994
Thanks to Daniel Berlin and Keith Walker for reviewing!
llvm-svn: 282611
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| .. | ||
| AArch64 | ||
| ARM | ||
| COFF | ||
| Generic | ||
| Inputs | ||
| Lanai | ||
| MIR | ||
| Mips | ||
| PDB | ||
| PowerPC | ||
| Sparc | ||
| SystemZ | ||
| WebAssembly | ||
| X86 | ||
| arm-relocs.test | ||
| debuglineinfo-macho.test | ||
| debuglineinfo.test | ||
| debugmacinfo.test | ||
| dwarfdump-64-bit-dwarf.test | ||
| dwarfdump-accel.test | ||
| dwarfdump-debug-frame-simple.test | ||
| dwarfdump-debug-loc-simple.test | ||
| dwarfdump-dump-flags.test | ||
| dwarfdump-dump-gdbindex.test | ||
| dwarfdump-dwp.test | ||
| dwarfdump-invalid.test | ||
| dwarfdump-line-dwo.test | ||
| dwarfdump-macho-relocs.test | ||
| dwarfdump-macho-universal.test | ||
| dwarfdump-objc.test | ||
| dwarfdump-pubnames.test | ||
| dwarfdump-ranges.test | ||
| dwarfdump-type-units.test | ||
| dwarfdump-zlib.test | ||
| dwo.ll | ||
| llvm-symbolizer-split-dwarf-empty.test | ||
| llvm-symbolizer-zlib.test | ||
| llvm-symbolizer.test | ||
| macro_link.ll | ||
| member-pointers.o | ||
| missing-abstract-variable.o | ||
| skeletoncu.ll | ||