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[X86] Drop the 64-bit alignment for LOW32_ADDR_ACCESS register class.

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The only 64-bit register in that register class is RIP and it will not
get spilled in the current ABIs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268963 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2016-05-09 19:50:30 +00:00
parent ce06f035f9
commit b8b6ac5e09
1 changed files with 3 additions and 2 deletions

5
lib/Target/X86/X86RegisterInfo.td

@ -421,11 +421,12 @@ def GR64_NOREX_NOSP : RegisterClass<"X86", [i64], 64,
// In such cases, it is fine to use RIP as we are sure the 32 high
// bits are not set. We do not need variants for NOSP as RIP is not
// allowed there.
// Alignment is 64 because we have RIP.
// RIP is not spilled anywhere for now, so stick to 32-bit alignment
// to save on memory space.
// FIXME: We could allow all 64bit registers, but we would need
// something to check that the 32 high bits are not set,
// which we do not have right now.
def LOW32_ADDR_ACCESS : RegisterClass<"X86", [i32], 64, (add GR32, RIP)>;
def LOW32_ADDR_ACCESS : RegisterClass<"X86", [i32], 32, (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.