https://llvm.org/bugs/show_bug.cgi?id=28208
Bug ID: 28208
Summary: Reassociate reports change made incorrectly
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: apilipe...@azulsystems.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
Reassociate pass returns true with no change made on the following function:
define i64 @test(i64 %a, i64 %b) {
%1 = and i64 %b, %a
ret i64 %1
}
opt -S reassociate.ll -reassociate -debug-pass=Executions
[2016-06-20 08:55:35.332437000] 0x1906670 Executing Pass 'Function Pass
Manager' on Module 'simple.ll'...
[2016-06-20 08:55:35.332704000] 0x1908770 Executing Pass 'Reassociate
expressions' on Function 'test'...
[2016-06-20 08:55:35.333682000] 0x1908770 *Made Modification* 'Reassociate
expressions' on Function 'test'...
[2016-06-20 08:55:35.333792000] 0x1908770 Freeing Pass 'Reassociate
expressions' on Function 'test'...
[2016-06-20 08:55:35.333837000] 0x1908770 Executing Pass 'Module Verifier'
on Function 'test'...
[2016-06-20 08:55:35.334012000] 0x1908770 Freeing Pass 'Module Verifier'
on Function 'test'...
[2016-06-20 08:55:35.334048000] 0x1906670 Made Modification 'Function Pass
Manager' on Module 'simple.ll'...
[2016-06-20 08:55:35.334077000] 0x1906670 Executing Pass 'Print module to
stderr' on Module 'simple.ll'...
It happens because it performs two distinct transformations which nullify each
other (canonicalizeOperands swaps arguments of an and and then
ReassociateExpression swaps them back).
--
You are receiving this mail because:
You are on the CC list for the bug.
_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
