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llvm-project/llvm/test/CodeGen/X86/ipra-reg-alias.ll

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IPRA: Fix RegMask calculation for alias registers This patch fixes a very subtle bug in regmask calculation. Thanks to zan jyu Wong <zyfwong@gmail.com> for bringing this to notice. For example if CL is only clobbered than CH should not be marked clobbered but CX, RCX and ECX should be mark clobbered. Previously for each modified register all of its aliases are marked clobbered by markRegClobbred() in RegUsageInfoCollector.cpp but that is wrong because when CL is clobbered then MRI::isPhysRegModified() will return true for CL, CX, ECX, RCX which is correct behavior but then for CX, EXC, RCX we mark CH also clobbered as CH is aliased to CX,ECX,RCX so markRegClobbred() is not required because isPhysRegModified already take cares of proper aliasing register. A very simple test case has been added to verify this change. Please find relevant bug report here : http://llvm.org/PR28567 Patch by Vivek Pandya <vivekvpandya@gmail.com> Differential Revision: https://reviews.llvm.org/D22400 llvm-svn: 276235
2016-07-21 11:50:39 +08:00
; RUN: llc -enable-ipra -print-regusage -o /dev/null 2>&1 < %s | FileCheck %s
target triple = "x86_64--"
define i8 @main(i8 %X) {
%inc = add i8 %X, 1
%inc2 = mul i8 %inc, 5
; Here only CL is clobbred so CH should not be clobbred, but CX, ECX and RCX
; should be clobbered.
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
; CHECK: main Clobbered Registers: $ah $al $ax $cl $cx $eax $ecx $eflags $rax $rcx
IPRA: Fix RegMask calculation for alias registers This patch fixes a very subtle bug in regmask calculation. Thanks to zan jyu Wong <zyfwong@gmail.com> for bringing this to notice. For example if CL is only clobbered than CH should not be marked clobbered but CX, RCX and ECX should be mark clobbered. Previously for each modified register all of its aliases are marked clobbered by markRegClobbred() in RegUsageInfoCollector.cpp but that is wrong because when CL is clobbered then MRI::isPhysRegModified() will return true for CL, CX, ECX, RCX which is correct behavior but then for CX, EXC, RCX we mark CH also clobbered as CH is aliased to CX,ECX,RCX so markRegClobbred() is not required because isPhysRegModified already take cares of proper aliasing register. A very simple test case has been added to verify this change. Please find relevant bug report here : http://llvm.org/PR28567 Patch by Vivek Pandya <vivekvpandya@gmail.com> Differential Revision: https://reviews.llvm.org/D22400 llvm-svn: 276235
2016-07-21 11:50:39 +08:00
ret i8 %inc2
}