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

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

llvm-svn: 268963

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/X86/X86RegisterInfo.td b/llvm/lib/Target/X86/X86RegisterInfo.td
index 797ff4f2e8e..29ce2860537 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.td
+++ b/llvm/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.