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Targets: commonize some stack realignment code

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This patch does the following:
* Fix FIXME on `needsStackRealignment`: it is now shared between multiple targets, implemented in `TargetRegisterInfo`, and isn't `virtual` anymore. This will break out-of-tree targets, silently if they used `virtual` and with a build error if they used `override`.
* Factor out `canRealignStack` as a `virtual` function on `TargetRegisterInfo`, by default only looks for the `no-realign-stack` function attribute.

Multiple targets duplicated the same `needsStackRealignment` code:
 - Aarch64.
 - ARM.
 - Mips almost: had extra `DEBUG` diagnostic, which the default implementation now has.
 - PowerPC.
 - WebAssembly.
 - x86 almost: has an extra `-force-align-stack` option, which the default implementation now has.

The default implementation of `needsStackRealignment` used to just return `false`. My current patch changes the behavior by simply using the above shared behavior. This affects:
 - AMDGPU
 - BPF
 - CppBackend
 - MSP430
 - NVPTX
 - Sparc
 - SystemZ
 - XCore
 - Out-of-tree targets
This is a breaking change! `make check` passes.

The only implementation of the `virtual` function (besides the slight different in x86) was Hexagon (which did `MF.getFrameInfo()->getMaxAlignment() > 8`), and potentially some out-of-tree targets. Hexagon now uses the default implementation.

`needsStackRealignment` was being overwritten in `<Target>GenRegisterInfo.inc`, to return `false` as the default also did. That was odd and is now gone.

Reviewers: sunfish

Subscribers: aemerson, llvm-commits, jfb

Differential Revision: http://reviews.llvm.org/D11160

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242727 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
JF Bastien
2015-07-20 22:51:32 +00:00
parent dfc9688bd9
commit 9994b911f4
19 changed files with 86 additions and 172 deletions
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19
lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
View File

@@ -66,22 +66,3 @@ WebAssemblyRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
const WebAssemblyFrameLowering *TFI = getFrameLowering(MF);
return Regs[TFI->hasFP(MF)][TT.isArch64Bit()];
}
bool WebAssemblyRegisterInfo::canRealignStack(const MachineFunction &MF) const {
return !MF.getFunction()->hasFnAttribute("no-realign-stack");
}
// FIXME: share this with other backends with identical implementation?
bool WebAssemblyRegisterInfo::needsStackRealignment(
const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const WebAssemblyFrameLowering *TFI = getFrameLowering(MF);
const Function *F = MF.getFunction();
unsigned StackAlign = TFI->getStackAlignment();
bool requiresRealignment =
((MFI->getMaxAlignment() > StackAlign) ||
F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
Attribute::StackAlignment));
return requiresRealignment && canRealignStack(MF);
}

4
lib/Target/WebAssembly/WebAssemblyRegisterInfo.h
View File

@@ -41,10 +41,6 @@ public:
// Debug information queries.
unsigned getFrameRegister(const MachineFunction &MF) const override;
// Base pointer (stack realignment) support.
bool canRealignStack(const MachineFunction &MF) const;
bool needsStackRealignment(const MachineFunction &MF) const override;
};
} // end namespace llvm