llvm-6502/test/CodeGen/PowerPC/add-fi.ll
Hal Finkel f329765d23 [PowerPC] Better lowering for add/or of a FrameIndex
If we have an add (or an or that is really an add), where one operand is a
FrameIndex and the other operand is a small constant, we can combine the
lowering of the FrameIndex (which is lowered as an add of the FI and a zero
offset) with the constant operand.

Amusingly, this is an old potential improvement entry from
lib/Target/PowerPC/README.txt which had never been resolved. In short, we used
to lower:

        %X = alloca { i32, i32 }
        %Y = getelementptr {i32,i32}* %X, i32 0, i32 1
        ret i32* %Y

as:

        addi 3, 1, -8
        ori 3, 3, 4
        blr

and now we produce:

        addi 3, 1, -4
        blr

which is much more sensible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224071 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-11 22:51:06 +00:00

25 lines
536 B
LLVM

; RUN: llc -mcpu=ppc64 < %s | FileCheck %s
target datalayout = "E-m:e-i64:64-n32:64"
target triple = "powerpc64-unknown-linux-gnu"
define i32* @test1() {
%X = alloca { i32, i32 }
%Y = getelementptr {i32,i32}* %X, i32 0, i32 1
ret i32* %Y
; CHECK-LABEL: @test1
; CHECK: addi 3, 1, -4
; CHECK: blr
}
define i32* @test2() {
%X = alloca { i32, i32, i32, i32 }
%Y = getelementptr {i32,i32,i32,i32}* %X, i32 0, i32 3
ret i32* %Y
; CHECK-LABEL: @test2
; CHECK: addi 3, 1, -4
; CHECK: blr
}