forked from OSchip/llvm-project
[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
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@ -110,19 +110,18 @@ bool RegUsageInfoCollector::runOnMachineFunction(MachineFunction &MF) {
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// Scan all the physical registers. When a register is defined in the current
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// function set it and all the aliasing registers as defined in the regmask.
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for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg) {
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// If a register is in the UsedPhysRegsMask set then mark it as defined.
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// All it's aliases will also be in the set, so we can skip setting
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// as defined all the aliases here.
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if (UsedPhysRegsMask.test(PReg)) {
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SetRegAsDefined(PReg);
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continue;
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}
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// If a register is defined by an instruction mark it as defined together
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// with all it's aliases.
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if (!MRI->def_empty(PReg)) {
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for (MCRegAliasIterator AI(PReg, TRI, true); AI.isValid(); ++AI)
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SetRegAsDefined(*AI);
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continue;
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}
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// If a register is in the UsedPhysRegsMask set then mark it as defined.
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// All clobbered aliases will also be in the set, so we can skip setting
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// as defined all the aliases here.
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if (UsedPhysRegsMask.test(PReg))
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SetRegAsDefined(PReg);
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}
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if (!TargetFrameLowering::isSafeForNoCSROpt(F)) {
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@ -0,0 +1,45 @@
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; Test that the set of used phys regs used by interprocedural register
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; allocation is correct for a test case where the called function (@fn2)
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; itself has a call (to @fn1). @fn1 defines %r0l, while @fn2 defines
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; %r0d. The RegUsageInfo for @fn2 must include %r0h.
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;
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; RUN: llc -mtriple=s390x-linux-gnu -mcpu=z13 -enable-ipra -print-regusage 2>&1 < %s \
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; RUN: | FileCheck %s
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;
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; CHECK: fn2 Clobbered Registers: {{.*}} $r0h
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@h = external global [0 x i32], align 4
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@n = external global i32*, align 8
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define void @fn1() {
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bb:
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br label %bb1
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bb1: ; preds = %bb1, %bb
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%tmp = getelementptr inbounds [0 x i32], [0 x i32]* @h, i64 0, i64 undef
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%tmp2 = load i32, i32* %tmp
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store i32 %tmp2, i32* undef
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br label %bb1
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}
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define void @fn2() {
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bb:
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br label %bb1
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bb1: ; preds = %bb
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br i1 undef, label %bb2, label %bb3
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bb2: ; preds = %bb1
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store i32* null, i32** @n
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unreachable
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bb3: ; preds = %bb1
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call void @fn1()
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unreachable
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}
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define void @main() {
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bb:
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call void @fn2()
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ret void
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}
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