diff options
author | Ian Romanick <[email protected]> | 2015-03-16 12:14:10 -0700 |
---|---|---|
committer | Ian Romanick <[email protected]> | 2015-03-19 15:35:42 -0700 |
commit | a44b95cd574ecab4a4c41c6380c82db6029ad114 (patch) | |
tree | 2f9f42da2cf6774b46bb59353ec43213471fcac4 /src/glsl/ir.h | |
parent | bf9d921936305e1514d4ce7a162c4f81eba3e9f5 (diff) |
glsl: Annotate as_foo functions that the this pointer cannot be NULL
We use the idiom
ir_foo *x = y->as_foo();
if (x == NULL)
return;
all over the place. GCC generates some quite lovely code for this.
One such example:
340a5b: 83 7d 18 04 cmpl $0x4,0x18(%rbp)
340a5f: 0f 85 06 04 00 00 jne 340e6b
340a65: 48 85 ed test %rbp,%rbp
340a68: 0f 84 fd 03 00 00 je 340e6b
This case used as_expression() (ir_type_expression is 4). Note that it
checks the ir_type, then checks that the pointer isn't NULL. There is
some disconnect in GCC around the condition in the as_foo functions.
return ir_type == ir_type_##TYPE ? (ir_##TYPE *) this : NULL; \
It believes "this" could be NULL, so it emits check outside the function
just for fun.
This patch uses assume() to tell GCC that it need not bother with extra
NULL checking of the pointer returned by the as_foo functions.
text data bss dec hex filename
4836430 158688 26248 5021366 4c9eb6 i965_dri-before.so
4836173 158688 26248 5021109 4c9db5 i965_dri-after.so
v2: Replace 'if (this == NULL) unreachable("this cannot be NULL")' with
assume(this != NULL). Suggested by Ilia Mirkin.
Signed-off-by: Ian Romanick <[email protected]>
Reviewed-by: Matt Turner <[email protected]>
Diffstat (limited to 'src/glsl/ir.h')
-rw-r--r-- | src/glsl/ir.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/glsl/ir.h b/src/glsl/ir.h index 25f2ecada0f..fdc22edf133 100644 --- a/src/glsl/ir.h +++ b/src/glsl/ir.h @@ -119,6 +119,7 @@ public: /*@{*/ class ir_rvalue *as_rvalue() { + assume(this != NULL); if (ir_type == ir_type_dereference_array || ir_type == ir_type_dereference_record || ir_type == ir_type_dereference_variable || @@ -132,6 +133,7 @@ public: class ir_dereference *as_dereference() { + assume(this != NULL); if (ir_type == ir_type_dereference_array || ir_type == ir_type_dereference_record || ir_type == ir_type_dereference_variable) @@ -141,6 +143,7 @@ public: class ir_jump *as_jump() { + assume(this != NULL); if (ir_type == ir_type_loop_jump || ir_type == ir_type_return || ir_type == ir_type_discard) @@ -151,6 +154,7 @@ public: #define AS_CHILD(TYPE) \ class ir_##TYPE * as_##TYPE() \ { \ + assume(this != NULL); \ return ir_type == ir_type_##TYPE ? (ir_##TYPE *) this : NULL; \ } AS_CHILD(variable) |