[RegUsageInfoCollector] Bugfix for handling of register aliases.

Don't assume the alias of a defined reg is always already in the set.

As the test case in https://bugs.llvm.org/show_bug.cgi?id=36587 discovered,
it is wrong to assume that all the aliases of the defined register in the
*current function* is already present in the UsedPhysRegsMask.

This patch changes this so that any definition in the current function of a
phys-reg always results in all its aliases inserted into the set of defined
registers.

Review: Quentin Colombet
https://reviews.llvm.org/D45157

llvm-svn: 331509
This commit is contained in:
Jonas Paulsson 2018-05-04 07:50:05 +00:00
parent 786032c1b7
commit 72fe760592
2 changed files with 51 additions and 7 deletions

View File

@ -110,19 +110,18 @@ bool RegUsageInfoCollector::runOnMachineFunction(MachineFunction &MF) {
// Scan all the physical registers. When a register is defined in the current
// function set it and all the aliasing registers as defined in the regmask.
for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg) {
// If a register is in the UsedPhysRegsMask set then mark it as defined.
// All it's aliases will also be in the set, so we can skip setting
// as defined all the aliases here.
if (UsedPhysRegsMask.test(PReg)) {
SetRegAsDefined(PReg);
continue;
}
// If a register is defined by an instruction mark it as defined together
// with all it's aliases.
if (!MRI->def_empty(PReg)) {
for (MCRegAliasIterator AI(PReg, TRI, true); AI.isValid(); ++AI)
SetRegAsDefined(*AI);
continue;
}
// If a register is in the UsedPhysRegsMask set then mark it as defined.
// All clobbered aliases will also be in the set, so we can skip setting
// as defined all the aliases here.
if (UsedPhysRegsMask.test(PReg))
SetRegAsDefined(PReg);
}
if (!TargetFrameLowering::isSafeForNoCSROpt(F)) {

View File

@ -0,0 +1,45 @@
; Test that the set of used phys regs used by interprocedural register
; allocation is correct for a test case where the called function (@fn2)
; itself has a call (to @fn1). @fn1 defines %r0l, while @fn2 defines
; %r0d. The RegUsageInfo for @fn2 must include %r0h.
;
; RUN: llc -mtriple=s390x-linux-gnu -mcpu=z13 -enable-ipra -print-regusage 2>&1 < %s \
; RUN: | FileCheck %s
;
; CHECK: fn2 Clobbered Registers: {{.*}} $r0h
@h = external global [0 x i32], align 4
@n = external global i32*, align 8
define void @fn1() {
bb:
br label %bb1
bb1: ; preds = %bb1, %bb
%tmp = getelementptr inbounds [0 x i32], [0 x i32]* @h, i64 0, i64 undef
%tmp2 = load i32, i32* %tmp
store i32 %tmp2, i32* undef
br label %bb1
}
define void @fn2() {
bb:
br label %bb1
bb1: ; preds = %bb
br i1 undef, label %bb2, label %bb3
bb2: ; preds = %bb1
store i32* null, i32** @n
unreachable
bb3: ; preds = %bb1
call void @fn1()
unreachable
}
define void @main() {
bb:
call void @fn2()
ret void
}