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[X86] Add a new LOW32_ADDR_ACCESS_RBP register class.

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ABIs like NaCl uses 32-bit addresses but have 64-bit frame.
The new register class reflects those constraints when choosing a
register class for a address access.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268796 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2016-05-06 21:10:53 +00:00
parent 93cbe6ed35
commit 72d2da5ca3
3 changed files with 17 additions and 4 deletions
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10
lib/Target/X86/X86RegisterInfo.cpp
View File

@ -166,7 +166,15 @@ X86RegisterInfo::getPointerRegClass(const MachineFunction &MF,
// we can still use 64-bit register as long as we know the high bits
// are zeros.
// Reflect that in the returned register class.
return Is64Bit ? &X86::LOW32_ADDR_ACCESSRegClass : &X86::GR32RegClass;
if (Is64Bit) {
// When the target also allows 64-bit frame pointer and we do have a
// frame, this is fine to use it for the address accesses as well.
const X86FrameLowering *TFI = getFrameLowering(MF);
return TFI->hasFP(MF) && TFI->Uses64BitFramePtr
? &X86::LOW32_ADDR_ACCESS_RBPRegClass
: &X86::LOW32_ADDR_ACCESSRegClass;
}
return &X86::GR32RegClass;
case 1: // Normal GPRs except the stack pointer (for encoding reasons).
if (Subtarget.isTarget64BitLP64())
return &X86::GR64_NOSPRegClass;

5
lib/Target/X86/X86RegisterInfo.td
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@ -427,6 +427,11 @@ def GR64_NOREX_NOSP : RegisterClass<"X86", [i64], 64,
// which we do not have right now.
def LOW32_ADDR_ACCESS : RegisterClass<"X86", [i32], 64, (add GR32, RIP)>;
// When RBP is used as a base pointer in a 32-bit addresses environement,
// this is also safe to use the full register to access addresses.
def LOW32_ADDR_ACCESS_RBP : RegisterClass<"X86", [i32], 64,
(add LOW32_ADDR_ACCESS, RBP)>;
// A class to support the 'A' assembler constraint: EAX then EDX.
def GR32_AD : RegisterClass<"X86", [i32], 32, (add EAX, EDX)>;

6
test/CodeGen/X86/x86-64-stack-and-frame-ptr.ll
View File

@ -1,6 +1,6 @@
; RUN: llc -mtriple=x86_64-pc-linux < %s | FileCheck %s
; RUN: llc -mtriple=x86_64-pc-linux-gnux32 < %s | FileCheck -check-prefix=X32ABI %s
; RUN: llc -mtriple=x86_64-pc-nacl < %s | FileCheck -check-prefix=NACL %s
; RUN: llc -verify-machineinstrs -mtriple=x86_64-pc-linux < %s | FileCheck %s
; RUN: llc -verify-machineinstrs -mtriple=x86_64-pc-linux-gnux32 < %s | FileCheck -check-prefix=X32ABI %s
; RUN: llc -verify-machineinstrs -mtriple=x86_64-pc-nacl < %s | FileCheck -check-prefix=NACL %s
; x32 uses %esp, %ebp as stack and frame pointers