Bug 43966 - redundant predicated checks not removed by VRP or jump-threading
Summary: redundant predicated checks not removed by VRP or jump-threading
Status: NEW
Alias: None
Product: gcc
Classification: Unclassified
Component: tree-optimization (show other bugs)
Version: 4.5.0
: P3 enhancement
Target Milestone: ---
Assignee: Not yet assigned to anyone
URL:
Keywords: missed-optimization
Depends on:
Blocks:
 
Reported: 2010-05-03 06:17 UTC by Hartmut Schirmer
Modified: 2021-07-26 08:22 UTC (History)
1 user (show)

See Also:
Host: i686-pc-mingw32
Target: i686-pc-mingw32
Build: i686-pc-mingw32
Known to work:
Known to fail:
Last reconfirmed: 2021-07-26 00:00:00

Attachments
Test case (355 bytes, text/plain)
2010-05-03 06:19 UTC, Hartmut Schirmer 		Details
Assembler listing (1.77 KB, text/plain)
2010-05-03 06:19 UTC, Hartmut Schirmer 		Details
View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Hartmut Schirmer 2010-05-03 06:17:54 UTC 
On attached test case GCC keeps the index range checks in
Vector::getValue although they're always true due to loop conditions

 # GNU C++ (GCC) version 4.5.0 (mingw32)
 # options passed:  -fpreprocessed yy5.ii -march=atom -mtune=atom -O2 -Wall
Comment 1 Hartmut Schirmer 2010-05-03 06:19:26 UTC 
Created attachment 20538 [details]
Test case

foo() uses a get method without checks and is ok, checks not optimized away in bar()
Comment 2 Hartmut Schirmer 2010-05-03 06:19:44 UTC 
Created attachment 20539 [details]
Assembler listing
Comment 3 Richard Biener 2010-05-03 09:59:47 UTC 
Well, this is another case where the predication by if (mData) makes this
hard to optimize.  Not impossible, but hard.