https://bugs.llvm.org/show_bug.cgi?id=40683
Bug ID: 40683
Summary: [OptimizePHIs + Expensive Checks] Bad machine code:
Virtual register killed in block, but needed live out.
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Common Code Generator Code
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Created attachment 21465
--> https://bugs.llvm.org/attachment.cgi?id=21465&action=edit
reduced testcase
bin/llc -mcpu=z10 -O3 tc_vregkill_liveout.ll -o -
*** Bad machine code: Virtual register killed in block, but needed live out.
***
- function: main
- basic block: %bb.2 (0x2aa66bceb88)
Virtual register %1 is used after the block.
LLVM ERROR: Found 1 machine code errors.
It seems that "Optimize machine instruction PHIs" is transforming this block,
which is inside a loop:
bb.2 (%ir-block.3):
; predecessors: %bb.1, %bb.3
successors: %bb.4(0x40000000), %bb.5(0x40000000); %bb.4(50.00%),
%bb.5(50.00%)
%3:gr32bit = PHI %1:gr32bit, %bb.1, %0:gr32bit, %bb.3
%4:gr32bit = IMPLICIT_DEF
CR killed %3:gr32bit, %4:gr32bit, implicit-def $cc
%5:gr32bit = LHI 0
%6:gr32bit = LHI -10
BRC 14, 4, %bb.4, implicit $cc
to
bb.2 (%ir-block.3):
; predecessors: %bb.1, %bb.3
successors: %bb.4(0x40000000), %bb.5(0x40000000); %bb.4(50.00%),
%bb.5(50.00%)
%4:gr32bit = IMPLICIT_DEF
CR killed %1:gr32bit, %4:gr32bit, implicit-def $cc
%5:gr32bit = LHI 0
%6:gr32bit = LHI -10
BRC 14, 4, %bb.4, implicit $cc
Both %1 and %0 are defined outside the loop, and %0 is a copy of %1. %1 should
not have the kill flag since it is used in the next iteration as well.
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
