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authorBjörn Gustavsson <[email protected]>2018-01-22 11:47:03 +0100
committerBjörn Gustavsson <[email protected]>2018-01-24 05:49:35 +0100
commitd5fbb64374247af0a90974a9c37a3eba93774f28 (patch)
tree9013252abf04723e12b33224bae200b72c483757 /lib/compiler
parentab6ac37e0c40331a2debd90f753ec2f4531e4701 (diff)
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Correct bug in beam_block:opt/2
The folling sequence in a block: {move,{x,1},{x,2}}. {move,{x,2},{x,2}}. would be incorrectly rewritten to: {move,{x,2},{x,2}}. (Which in turn would be optimized away a little bit later.)
Diffstat (limited to 'lib/compiler')
-rw-r--r--lib/compiler/src/beam_block.erl2
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index 7f6d3a75ae..18f325f172 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -231,7 +231,7 @@ alloc_may_pass({set,_,_,_}) -> true.
%% Optimize the instruction stream inside a basic block.
opt([{set,[X],[X],move}|Is]) -> opt(Is);
-opt([{set,[X],_,move},{set,[X],_,move}=I|Is]) ->
+opt([{set,[Dst],_,move},{set,[Dst],[Src],move}=I|Is]) when Dst =/= Src ->
opt([I|Is]);
opt([{set,[{x,0}],[S1],move}=I1,{set,[D2],[{x,0}],move}|Is]) ->
opt([I1,{set,[D2],[S1],move}|Is]);