More verbose -print-allocs messages. Initial commit.

[ebak]

This change intends to provide more verbose -print-allocs messages by naming the escaping intermediate variable or type.
Currently it is tested only with the unit tests.

Here are the modified messages, generated by allocs_test.go:

makeslice.buf size is not constant
makeslice4 size 300 exceeds maximum stack allocation size 256
makeslice6 escapes at line 30
FloatType escapes at line 37
varargs12 escapes at line 44
slicelit14 escapes at line 47
n4 escapes at line 51
n5 escapes at line 51
makeslice escapes at line 108
b escapes at line 117
Arg 0 of main.scaleVector3() call escapes at line 122
b escapes at unknown line

[dgryski]

Seems good but someone else a bit more familiar with this code should take a look.

[ebak]

Now the messages from the allocs_test.go unit test are looking like this:

allocs2.go:26: makeslice.buf size is not constant
allocs2.go:28: makeslice4 size 300 exceeds maximum stack allocation size 256
allocs2.go:31: makeslice6 escapes at line 32
allocs2.go:38: Arg 0 (type: basic:complex128) of main.useInterface() escapes at line 40
allocs2.go:43: Arg 0 (type: array:3:basic:int32) of main.useInterface() escapes at line 43
allocs2.go:50: varargs12 escapes at line 50
allocs2.go:52: slicelit14 escapes at line 53
allocs2.go:55: n4 escapes at line 57
allocs2.go:56: n5 escapes at line 57
allocs2.go:132: makeslice escapes at line 133
allocs2.go:139: b escapes at line 142
allocs2.go:148: Arg 0 of main.scaleVector3() escapes at line 149
allocs2.go:150: complit1 escapes at line 151
allocs2.go:150: complit2 escapes at line 151
allocs2.go:156: Arg 1 (type: pointer:named:main.vector3) of main.useInterfaces() escapes at line 156
allocs2.go:156: Arg 4 (type: pointer:named:main.vector3) of main.useInterfaces() escapes at line 156
allocs2.go:160: Arg 1 (type: pointer:named:main.vector3) of main.useInterfaces() escapes at line 160
allocs2.go:160: Arg 4 (type: pointer:named:main.vector3) of main.useInterfaces() escapes at line 160
allocs2.go:171: b escapes at unknown line
allocs2.go:179: varargs escapes at line 179
allocs2.go:184: main.theError escapes at line 184
allocs2.go:188: main.theError escapes at line 188
allocs2.go:193: array:3:basic:int32 escapes at line 193

I also executed this -print-allocs on one of my projects and I got these results:

heap/storage/unsafe_arraylist.go:64:30: heap allocation: 16 bytes escapes at line 64
heap/checks/string_test.go:35:30: heap allocation: 16 bytes escapes at line 35
heap/checks/string_test.go:13:2: heap allocation: alloc escapes at line 16   // --- here "alloc" is a variable name
heap/checks/string_test.go:10:17: heap allocation: t1 escapes at line 16
heap/checks/string_test.go:48:79: heap allocation: 96 bytes escapes at line 48
heap/checks/string_test.go:45:21: heap allocation: 16 bytes escapes at line 48
heap/checks/str_test.go:24:3: heap allocation: str escapes at line 14
heap/checks/str_test.go:17:2: heap allocation: alloc escapes at line 14      // --- here "alloc" is a variable name
heap/checks/utils.go:16:25: heap allocation: 16 bytes escapes at line 16
heap/internal/holecache/simple/simple.go:22:15: heap allocation: complit escapes at line 22
heap/internal/heap/allocator.go:47:14: heap allocation: makeslice.buf escapes at line 51
heap/internal/heap/allocator.go:235:20: heap allocation: heap/internal/heap.AllocError escapes at line 235
heap/internal/heap/allocator.go:218:20: heap allocation: heap/internal/heap.AllocError escapes at line 218
heap/internal/heap/allocator.go:213:20: heap allocation: heap/internal/heap.AllocError escapes at line 213
heap/internal/heap/allocator.go:179:22: heap allocation: heap/internal/heap.AllocError escapes at line 179
heap/internal/heap/allocator.go:386:20: heap allocation: heap/internal/heap.AllocError escapes at line 386
heap/internal/heap/allocator.go:374:23: heap allocation: heap/internal/heap.AllocError escapes at line 374
heap/internal/heap/allocator.go:311:31: heap allocation: heap/internal/heap.AllocError escapes at line 314
heap/internal/heap/allocator.go:199:29: heap allocation: heap/internal/heap.AllocError escapes at line 182
heap/internal/heap/allocator.go:196:33: heap allocation: heap/internal/heap.AllocError escapes at line 196

Of course it is far from being perfect, but probably there is more possibility for mining out the name and/or type of the escaped object from LLVM IR and this change could be a stub for that.

[b0ch3nski]

Seems dumpIR is unused?

[ebak]

Yes, anyone who touches this code can use it for debugging.