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llvm-mirror/test/CodeGen/SystemZ/cond-move-02.ll
Ulrich Weigand 01646554f8 [SystemZ] Do not use glue to represent condition code dependencies
Currently, an instruction setting the condition code is linked to
the instruction using the condition code via a "glue" link in the
SelectionDAG.  This has a number of drawbacks; in particular, it
means the same CC cannot be used by multiple users.  It also makes
it more difficult to efficiently implement SADDO et. al.

This patch changes the back-end to represent CC dependencies as
normal values during SelectionDAG matching, along the lines of
how this is handled in the X86 back-end already.

In addition to the core mechanics of updating all relevant patterns,
this requires a number of additional changes:

- We now need to be able to spill/restore a CC value into a GPR
  if necessary.  This means providing a copyPhysReg implementation
  for moves involving CC, and defining getCrossCopyRegClass.

- Since we still prefer to avoid such spills, we provide an override
  for IsProfitableToFold to avoid creating a merged LOAD / ICMP if
  this would result in multiple users of the CC.

- combineCCMask no longer requires a single CC user, and no longer
  need to be careful about preventing invalid glue/chain cycles.

- emitSelect needs to be more careful in marking CC live-in to
  the basic block it generates.  Also, we can now optimize the
  case of multiple subsequent selects with the same condition
  just like X86 does.

llvm-svn: 331202
2018-04-30 17:52:32 +00:00

139 lines
2.7 KiB
LLVM

; Test LOCHI and LOCGHI.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 -verify-machineinstrs | FileCheck %s
define i32 @f1(i32 %x) {
; CHECK-LABEL: f1:
; CHECK: chi %r2, 0
; CHECK: lhi %r2, 0
; CHECK: lochilh %r2, 42
; CHECK: br %r14
%cond = icmp ne i32 %x, 0
%res = select i1 %cond, i32 42, i32 0
ret i32 %res
}
define i32 @f2(i32 %x, i32 %y) {
; CHECK-LABEL: f2:
; CHECK: chi %r2, 0
; CHECK: lochilh %r3, 42
; CHECK: br %r14
%cond = icmp ne i32 %x, 0
%res = select i1 %cond, i32 42, i32 %y
ret i32 %res
}
define i32 @f3(i32 %x, i32 %y) {
; CHECK-LABEL: f3:
; CHECK: chi %r2, 0
; CHECK: lochie %r3, 42
; CHECK: br %r14
%cond = icmp ne i32 %x, 0
%res = select i1 %cond, i32 %y, i32 42
ret i32 %res
}
define i64 @f4(i64 %x) {
; CHECK-LABEL: f4:
; CHECK: cghi %r2, 0
; CHECK: lghi %r2, 0
; CHECK: locghilh %r2, 42
; CHECK: br %r14
%cond = icmp ne i64 %x, 0
%res = select i1 %cond, i64 42, i64 0
ret i64 %res
}
define i64 @f5(i64 %x, i64 %y) {
; CHECK-LABEL: f5:
; CHECK: cghi %r2, 0
; CHECK: locghilh %r3, 42
; CHECK: br %r14
%cond = icmp ne i64 %x, 0
%res = select i1 %cond, i64 42, i64 %y
ret i64 %res
}
define i64 @f6(i64 %x, i64 %y) {
; CHECK-LABEL: f6:
; CHECK: cghi %r2, 0
; CHECK: locghie %r3, 42
; CHECK: br %r14
%cond = icmp ne i64 %x, 0
%res = select i1 %cond, i64 %y, i64 42
ret i64 %res
}
; Check that we also get LOCHI as a result of early if-conversion.
define i32 @f7(i32 %x, i32 %y) {
; CHECK-LABEL: f7:
; CHECK: chi %r2, 0
; CHECK: lochie %r3, 42
; CHECK: br %r14
entry:
%cond = icmp ne i32 %x, 0
br i1 %cond, label %if.then, label %return
if.then:
br label %return
return:
%res = phi i32 [ %y, %if.then ], [ 42, %entry ]
ret i32 %res
}
; ... and the same for LOCGHI.
define i64 @f8(i64 %x, i64 %y) {
; CHECK-LABEL: f8:
; CHECK: cghi %r2, 0
; CHECK: locghie %r3, 42
; CHECK: br %r14
entry:
%cond = icmp ne i64 %x, 0
br i1 %cond, label %if.then, label %return
if.then:
br label %return
return:
%res = phi i64 [ %y, %if.then ], [ 42, %entry ]
ret i64 %res
}
; Check that inverting the condition works as well.
define i32 @f9(i32 %x, i32 %y) {
; CHECK-LABEL: f9:
; CHECK: chi %r2, 0
; CHECK: lochilh %r3, 42
; CHECK: br %r14
entry:
%cond = icmp ne i32 %x, 0
br i1 %cond, label %if.then, label %return
if.then:
br label %return
return:
%res = phi i32 [ 42, %if.then ], [ %y, %entry ]
ret i32 %res
}
; ... and the same for LOCGHI.
define i64 @f10(i64 %x, i64 %y) {
; CHECK-LABEL: f10:
; CHECK: cghi %r2, 0
; CHECK: locghilh %r3, 42
; CHECK: br %r14
entry:
%cond = icmp ne i64 %x, 0
br i1 %cond, label %if.then, label %return
if.then:
br label %return
return:
%res = phi i64 [ 42, %if.then ], [ %y, %entry ]
ret i64 %res
}