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-rw-r--r--lib/compiler/src/beam_utils.erl19
1 files changed, 18 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 1195a6b560..dcdbaa0bab 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -22,7 +22,7 @@
-module(beam_utils).
-export([is_killed_block/2,is_killed/3,is_killed_at/3,
- is_not_used/3,
+ is_not_used/3,usage/3,
empty_label_index/0,index_label/3,index_labels/1,replace_labels/4,
code_at/2,bif_to_test/3,is_pure_test/1,
live_opt/1,delete_live_annos/1,combine_heap_needs/2,
@@ -62,6 +62,23 @@
{lbl :: code_index(), %Label to code index.
res :: result_cache()}). %Result cache for each label.
+%% usage(Register, [Instruction], State) -> killed|not_used|used.
+%% Determine the usage of Register in the instruction sequence.
+%% The return value is one of:
+%%
+%% killed - The register is not used in any way.
+%% not_used - The register is referenced only by an allocating instruction
+%% (the actual value does not matter).
+%% used - The register is used (its value do matter).
+
+-spec usage(beam_asm:reg(), [instruction()], code_index()) ->
+ 'killed' | 'not_used' | 'used'.
+
+usage(R, Is, D) ->
+ St = #live{lbl=D,res=gb_trees:empty()},
+ {Usage,_} = check_liveness(R, Is, St),
+ Usage.
+
%% is_killed_block(Register, [Instruction]) -> true|false
%% Determine whether a register is killed by the instruction sequence inside