llvm-6502/test/CodeGen/PowerPC/ppc64-vaarg-int.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

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LLVM

target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v128:128:128-n32:64"
target triple = "powerpc64-unknown-linux-gnu"
; RUN: llc < %s | FileCheck %s
define i32 @intvaarg(i32 %a, ...) nounwind {
entry:
%va = alloca i8*, align 8
%va1 = bitcast i8** %va to i8*
call void @llvm.va_start(i8* %va1)
%0 = va_arg i8** %va, i32
%sub = sub nsw i32 %a, %0
ret i32 %sub
}
declare void @llvm.va_start(i8*) nounwind
; CHECK: @intvaarg
; Make sure that the va pointer is incremented by 8 (not 4).
; CHECK: addi{{.*}}, 1, 64