llvm-6502/test/CodeGen/SystemZ/shift-10.ll
Richard Sandiford 80a3301b37 [SystemZ] Optimize (sext (ashr (shl ...), ...))
...into (ashr (shl (anyext X), ...), ...), which requires one fewer
instruction.  The (anyext X) can sometimes be simplified too.

I didn't do this in DAGCombiner because widening shifts isn't a win
on all targets.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199114 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-13 15:17:53 +00:00

92 lines
2.1 KiB
LLVM

; Test compound shifts.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
; Test a shift right followed by a sign extension. This can use two shifts.
define i64 @f1(i32 %a) {
; CHECK-LABEL: f1:
; CHECK: sllg [[REG:%r[0-5]]], %r2, 62
; CHECK: srag %r2, [[REG]], 63
; CHECK: br %r14
%shr = lshr i32 %a, 1
%trunc = trunc i32 %shr to i1
%ext = sext i1 %trunc to i64
ret i64 %ext
}
; ...and again with the highest shift count that doesn't reduce to an
; ashr/sext pair.
define i64 @f2(i32 %a) {
; CHECK-LABEL: f2:
; CHECK: sllg [[REG:%r[0-5]]], %r2, 33
; CHECK: srag %r2, [[REG]], 63
; CHECK: br %r14
%shr = lshr i32 %a, 30
%trunc = trunc i32 %shr to i1
%ext = sext i1 %trunc to i64
ret i64 %ext
}
; Test a left shift that of an extended right shift in a case where folding
; is possible.
define i64 @f3(i32 %a) {
; CHECK-LABEL: f3:
; CHECK: risbg %r2, %r2, 27, 181, 9
; CHECK: br %r14
%shr = lshr i32 %a, 1
%ext = zext i32 %shr to i64
%shl = shl i64 %ext, 10
%and = and i64 %shl, 137438952960
ret i64 %and
}
; ...and again with a larger right shift.
define i64 @f4(i32 %a) {
; CHECK-LABEL: f4:
; CHECK: risbg %r2, %r2, 30, 158, 3
; CHECK: br %r14
%shr = lshr i32 %a, 30
%ext = sext i32 %shr to i64
%shl = shl i64 %ext, 33
%and = and i64 %shl, 8589934592
ret i64 %and
}
; Repeat the previous test in a case where all bits outside the
; bottom 3 matter.
define i64 @f5(i32 %a) {
; CHECK-LABEL: f5:
; CHECK: risbg %r2, %r2, 29, 158, 3
; CHECK: lhi %r2, 7
; CHECK: br %r14
%shr = lshr i32 %a, 30
%ext = sext i32 %shr to i64
%shl = shl i64 %ext, 33
%or = or i64 %shl, 7
ret i64 %or
}
; Test that SRA gets replaced with SRL if the sign bit is the only one
; that matters.
define i64 @f6(i64 %a) {
; CHECK-LABEL: f6:
; CHECK: risbg %r2, %r2, 55, 183, 19
; CHECK: br %r14
%shl = shl i64 %a, 10
%shr = ashr i64 %shl, 60
%and = and i64 %shr, 256
ret i64 %and
}
; Test another form of f1.
define i64 @f7(i32 %a) {
; CHECK-LABEL: f7:
; CHECK: sllg [[REG:%r[0-5]]], %r2, 62
; CHECK: srag %r2, [[REG]], 63
; CHECK: br %r14
%1 = shl i32 %a, 30
%sext = ashr i32 %1, 31
%ext = sext i32 %sext to i64
ret i64 %ext
}