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llvm-mirror/test/CodeGen/Mips/global-pointer-reg.ll
Akira Hatanaka 3b3ee53886 Add an option to use a virtual register as the global base register instead of
reserving a physical register ($gp or $28) for that purpose.

This will completely eliminate loads that restore the value of $gp after every
function call, if the register allocator assigns a callee-saved register, or
eliminate unnecessary loads if it assigns a temporary register. 

example:

.cpload $25       // set $gp.
...
.cprestore 16     // store $gp to stack slot 16($sp).
...
jalr $25          // function call. clobbers $gp.
lw $gp, 16($sp)   // not emitted if callee-saved reg is chosen.
...
lw $2, 4($gp)
...
jalr $25          // function call.
lw $gp, 16($sp)   // not emitted if $gp is not live after this instruction.
...

llvm-svn: 151402
2012-02-24 22:34:47 +00:00

23 lines
611 B
LLVM

; RUN: llc < %s -march=mipsel -mips-fix-global-base-reg=false | FileCheck %s
@g0 = external global i32
@g1 = external global i32
@g2 = external global i32
define void @foo1() nounwind {
entry:
; CHECK-NOT: .cpload
; CHECK-NOT: .cprestore
; CHECK: lui $[[R0:[0-9]+]], %hi(_gp_disp)
; CHECK: addiu $[[R1:[0-9]+]], $[[R0]], %lo(_gp_disp)
; CHECK: addu $[[GP:[0-9]+]], $[[R1]], $25
; CHECK: lw ${{[0-9]+}}, %call16(foo2)($[[GP]])
tail call void @foo2(i32* @g0) nounwind
tail call void @foo2(i32* @g1) nounwind
tail call void @foo2(i32* @g2) nounwind
ret void
}
declare void @foo2(i32*)