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llvm-project/llvm/test/CodeGen/X86/unreachable-mbb-undef-phi.mir

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Recommit [UnreachableBlockElim] Use COPY if PHI input is undef This time invoking llc with "-march=x86-64" in the testcase, so we don't assume the default target is x86. Summary: If we have %vreg0<def> = PHI %vreg2<undef>, <BB#0>, %vreg3, <BB#2>; GR32:%vreg0,%vreg2,%vreg3 %vreg3<def,tied1> = ADD32ri8 %vreg0<kill,tied0>, 1, %EFLAGS<imp-def>; GR32:%vreg3,%vreg0 then we can't just change %vreg0 into %vreg3, since %vreg2 is actually undef. We would have to also copy the undef flag to be able to change the register. Instead we deal with this case like other cases where we can't just replace the register: we insert a COPY. The code creating the COPY already copied all flags from the PHI input, so the undef flag will be transferred as it should. Reviewers: kparzysz Reviewed By: kparzysz Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D38235 llvm-svn: 314882
2017-10-04 15:42:45 +08:00
# RUN: llc -march=x86-64 %s -o - -run-pass=processimpdefs -run-pass=unreachable-mbb-elimination | FileCheck %s
---
name: f
tracksRegLiveness: true
registers:
- { id: 0, class: gr32, preferred-register: '' }
- { id: 1, class: gr32, preferred-register: '' }
- { id: 2, class: gr32, preferred-register: '' }
body: |
bb.0:
%0 = IMPLICIT_DEF
JMP_1 %bb.1
bb.1:
%1 = PHI %0, %bb.0, %2, %bb.2
Followup on Proposal to move MIR physical register namespace to '$' sigil. Discussed here: http://lists.llvm.org/pipermail/llvm-dev/2018-January/120320.html In preparation for adding support for named vregs we are changing the sigil for physical registers in MIR to '$' from '%'. This will prevent name clashes of named physical register with named vregs. llvm-svn: 323922
2018-02-01 06:04:26 +08:00
%2 = ADD32ri8 killed %1, 1, implicit-def $eflags
Recommit [UnreachableBlockElim] Use COPY if PHI input is undef This time invoking llc with "-march=x86-64" in the testcase, so we don't assume the default target is x86. Summary: If we have %vreg0<def> = PHI %vreg2<undef>, <BB#0>, %vreg3, <BB#2>; GR32:%vreg0,%vreg2,%vreg3 %vreg3<def,tied1> = ADD32ri8 %vreg0<kill,tied0>, 1, %EFLAGS<imp-def>; GR32:%vreg3,%vreg0 then we can't just change %vreg0 into %vreg3, since %vreg2 is actually undef. We would have to also copy the undef flag to be able to change the register. Instead we deal with this case like other cases where we can't just replace the register: we insert a COPY. The code creating the COPY already copied all flags from the PHI input, so the undef flag will be transferred as it should. Reviewers: kparzysz Reviewed By: kparzysz Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D38235 llvm-svn: 314882
2017-10-04 15:42:45 +08:00
JMP_1 %bb.3
bb.2:
JMP_1 %bb.1
bb.3:
...
# bb2 above is dead and should be removed and the PHI should be replaced with a
# COPY from an undef value since the bb0 value in the PHI is undef.
# CHECK: bb.0:
# CHECK: successors: %bb.1
# CHECK: JMP_1 %bb.1
# CHECK: bb.1:
# CHECK: successors: %bb.2
MIR: Print the register class or bank in vreg defs This updates the MIRPrinter to include the regclass when printing virtual register defs, which is already valid syntax for the parser. That is, given 64 bit %0 and %1 in a "gpr" regbank, %1(s64) = COPY %0(s64) would now be written as %1:gpr(s64) = COPY %0(s64) While this change alone introduces a bit of redundancy with the registers block, it allows us to update the tests to be more concise and understandable and brings us closer to being able to remove the registers block completely. Note: We generally only print the class in defs, but there is one exception. If there are uses without any defs whatsoever, we'll print the class on all uses. I'm not completely convinced this comes up in meaningful machine IR, but for now the MIRParser and MachineVerifier both accept that kind of stuff, so we don't want to have a situation where we can print something we can't parse. llvm-svn: 316479
2017-10-25 02:04:54 +08:00
# CHECK: [[TMP1:%[0-9]+]]:gr32 = COPY undef %{{[0-9]+}}
# CHECK: %{{[0-9]+}}:gr32 = ADD32ri8 killed [[TMP1]], 1
Recommit [UnreachableBlockElim] Use COPY if PHI input is undef This time invoking llc with "-march=x86-64" in the testcase, so we don't assume the default target is x86. Summary: If we have %vreg0<def> = PHI %vreg2<undef>, <BB#0>, %vreg3, <BB#2>; GR32:%vreg0,%vreg2,%vreg3 %vreg3<def,tied1> = ADD32ri8 %vreg0<kill,tied0>, 1, %EFLAGS<imp-def>; GR32:%vreg3,%vreg0 then we can't just change %vreg0 into %vreg3, since %vreg2 is actually undef. We would have to also copy the undef flag to be able to change the register. Instead we deal with this case like other cases where we can't just replace the register: we insert a COPY. The code creating the COPY already copied all flags from the PHI input, so the undef flag will be transferred as it should. Reviewers: kparzysz Reviewed By: kparzysz Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D38235 llvm-svn: 314882
2017-10-04 15:42:45 +08:00
# CHECK: JMP_1 %bb.2
# CHECK: bb.2: