llvm-6502/test/CodeGen/X86/sink-hoist.ll
Bill Wendling 869d60d39d Machine sink could potentially sink instructions into a block where the physical
registers it defines then interfere with an existing preg live range.

For instance, if we had something like these machine instructions:

BB#0
  ... = imul ... EFLAGS<imp-def,dead>
  test ..., EFLAGS<imp-def>
  jcc BB#2 EFLAGS<imp-use>

BB#1
  ... ; fallthrough to BB#2

BB#2
  ... ; No code that defines EFLAGS
  jcc ... EFLAGS<imp-use>

Machine sink will come along, see that imul implicitly defines EFLAGS, but
because it's "dead", it assumes that it can move imul into BB#2. But when it
does, imul's "dead" imp-def of EFLAGS is raised from the dead (a zombie) and
messes up the condition code for the jump (and pretty much anything else which
relies upon it being correct).

The solution is to know which pregs are live going into a basic block. However,
that information isn't calculated at this point. Nor does the LiveVariables pass
take into account non-allocatable physical registers. In lieu of this, we do a
*very* conservative pass through the basic block to determine if a preg is live
coming out of it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105387 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-03 07:54:20 +00:00

156 lines
6.7 KiB
LLVM

; RUN: llc < %s -march=x86-64 -asm-verbose=false -mtriple=x86_64-unknown-linux-gnu -post-RA-scheduler=true | FileCheck %s
; Currently, floating-point selects are lowered to CFG triangles.
; This means that one side of the select is always unconditionally
; evaluated, however with MachineSink we can sink the other side so
; that it's conditionally evaluated.
; CHECK: foo:
; CHECK: divsd
; CHECK-NEXT: testb $1, %dil
; CHECK-NEXT: jne
; CHECK-NEXT: divsd
define double @foo(double %x, double %y, i1 %c) nounwind {
%a = fdiv double %x, 3.2
%b = fdiv double %y, 3.3
%z = select i1 %c, double %a, double %b
ret double %z
}
; Hoist floating-point constant-pool loads out of loops.
; CHECK: bar:
; CHECK: movsd
; CHECK: align
define void @bar(double* nocapture %p, i64 %n) nounwind {
entry:
%0 = icmp sgt i64 %n, 0
br i1 %0, label %bb, label %return
bb:
%i.03 = phi i64 [ 0, %entry ], [ %3, %bb ]
%scevgep = getelementptr double* %p, i64 %i.03
%1 = load double* %scevgep, align 8
%2 = fdiv double 3.200000e+00, %1
store double %2, double* %scevgep, align 8
%3 = add nsw i64 %i.03, 1
%exitcond = icmp eq i64 %3, %n
br i1 %exitcond, label %return, label %bb
return:
ret void
}
; Sink instructions with dead EFLAGS defs.
; FIXME: Unfail the zzz test if we can correctly mark pregs with the kill flag.
;
; See <rdar://problem/8030636>. This test isn't valid after we made machine
; sinking more conservative about sinking instructions that define a preg into a
; block when we don't know if the preg is killed within the current block.
; FIXMEHECK: zzz:
; FIXMEHECK: je
; FIXMEHECK-NEXT: orb
; define zeroext i8 @zzz(i8 zeroext %a, i8 zeroext %b) nounwind readnone {
; entry:
; %tmp = zext i8 %a to i32 ; <i32> [#uses=1]
; %tmp2 = icmp eq i8 %a, 0 ; <i1> [#uses=1]
; %tmp3 = or i8 %b, -128 ; <i8> [#uses=1]
; %tmp4 = and i8 %b, 127 ; <i8> [#uses=1]
; %b_addr.0 = select i1 %tmp2, i8 %tmp4, i8 %tmp3 ; <i8> [#uses=1]
; ret i8 %b_addr.0
; }
; Codegen should hoist and CSE these constants.
; CHECK: vv:
; CHECK: LCPI2_0(%rip), %xmm0
; CHECK: LCPI2_1(%rip), %xmm1
; CHECK: LCPI2_2(%rip), %xmm2
; CHECK: align
; CHECK-NOT: LCPI
; CHECK: ret
@_minusZero.6007 = internal constant <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00> ; <<4 x float>*> [#uses=0]
@twoTo23.6008 = internal constant <4 x float> <float 8.388608e+06, float 8.388608e+06, float 8.388608e+06, float 8.388608e+06> ; <<4 x float>*> [#uses=0]
define void @vv(float* %y, float* %x, i32* %n) nounwind ssp {
entry:
br label %bb60
bb: ; preds = %bb60
%0 = bitcast float* %x_addr.0 to <4 x float>* ; <<4 x float>*> [#uses=1]
%1 = load <4 x float>* %0, align 16 ; <<4 x float>> [#uses=4]
%tmp20 = bitcast <4 x float> %1 to <4 x i32> ; <<4 x i32>> [#uses=1]
%tmp22 = and <4 x i32> %tmp20, <i32 2147483647, i32 2147483647, i32 2147483647, i32 2147483647> ; <<4 x i32>> [#uses=1]
%tmp23 = bitcast <4 x i32> %tmp22 to <4 x float> ; <<4 x float>> [#uses=1]
%tmp25 = bitcast <4 x float> %1 to <4 x i32> ; <<4 x i32>> [#uses=1]
%tmp27 = and <4 x i32> %tmp25, <i32 -2147483648, i32 -2147483648, i32 -2147483648, i32 -2147483648> ; <<4 x i32>> [#uses=2]
%tmp30 = call <4 x float> @llvm.x86.sse.cmp.ps(<4 x float> %tmp23, <4 x float> <float 8.388608e+06, float 8.388608e+06, float 8.388608e+06, float 8.388608e+06>, i8 5) ; <<4 x float>> [#uses=1]
%tmp34 = bitcast <4 x float> %tmp30 to <4 x i32> ; <<4 x i32>> [#uses=1]
%tmp36 = xor <4 x i32> %tmp34, <i32 -1, i32 -1, i32 -1, i32 -1> ; <<4 x i32>> [#uses=1]
%tmp37 = and <4 x i32> %tmp36, <i32 1258291200, i32 1258291200, i32 1258291200, i32 1258291200> ; <<4 x i32>> [#uses=1]
%tmp42 = or <4 x i32> %tmp37, %tmp27 ; <<4 x i32>> [#uses=1]
%tmp43 = bitcast <4 x i32> %tmp42 to <4 x float> ; <<4 x float>> [#uses=2]
%tmp45 = fadd <4 x float> %1, %tmp43 ; <<4 x float>> [#uses=1]
%tmp47 = fsub <4 x float> %tmp45, %tmp43 ; <<4 x float>> [#uses=2]
%tmp49 = call <4 x float> @llvm.x86.sse.cmp.ps(<4 x float> %1, <4 x float> %tmp47, i8 1) ; <<4 x float>> [#uses=1]
%2 = bitcast <4 x float> %tmp49 to <4 x i32> ; <<4 x i32>> [#uses=1]
%3 = call <4 x float> @llvm.x86.sse2.cvtdq2ps(<4 x i32> %2) nounwind readnone ; <<4 x float>> [#uses=1]
%tmp53 = fadd <4 x float> %tmp47, %3 ; <<4 x float>> [#uses=1]
%tmp55 = bitcast <4 x float> %tmp53 to <4 x i32> ; <<4 x i32>> [#uses=1]
%tmp57 = or <4 x i32> %tmp55, %tmp27 ; <<4 x i32>> [#uses=1]
%tmp58 = bitcast <4 x i32> %tmp57 to <4 x float> ; <<4 x float>> [#uses=1]
%4 = bitcast float* %y_addr.0 to <4 x float>* ; <<4 x float>*> [#uses=1]
store <4 x float> %tmp58, <4 x float>* %4, align 16
%5 = getelementptr float* %x_addr.0, i64 4 ; <float*> [#uses=1]
%6 = getelementptr float* %y_addr.0, i64 4 ; <float*> [#uses=1]
%7 = add i32 %i.0, 4 ; <i32> [#uses=1]
br label %bb60
bb60: ; preds = %bb, %entry
%i.0 = phi i32 [ 0, %entry ], [ %7, %bb ] ; <i32> [#uses=2]
%x_addr.0 = phi float* [ %x, %entry ], [ %5, %bb ] ; <float*> [#uses=2]
%y_addr.0 = phi float* [ %y, %entry ], [ %6, %bb ] ; <float*> [#uses=2]
%8 = load i32* %n, align 4 ; <i32> [#uses=1]
%9 = icmp sgt i32 %8, %i.0 ; <i1> [#uses=1]
br i1 %9, label %bb, label %return
return: ; preds = %bb60
ret void
}
declare <4 x float> @llvm.x86.sse.cmp.ps(<4 x float>, <4 x float>, i8) nounwind readnone
declare <4 x float> @llvm.x86.sse2.cvtdq2ps(<4 x i32>) nounwind readnone
; CodeGen should use the correct register class when extracting
; a load from a zero-extending load for hoisting.
; CHECK: default_get_pch_validity:
; CHECK: movl cl_options_count(%rip), %ecx
@cl_options_count = external constant i32 ; <i32*> [#uses=2]
define void @default_get_pch_validity() nounwind {
entry:
%tmp4 = load i32* @cl_options_count, align 4 ; <i32> [#uses=1]
%tmp5 = icmp eq i32 %tmp4, 0 ; <i1> [#uses=1]
br i1 %tmp5, label %bb6, label %bb2
bb2: ; preds = %bb2, %entry
%i.019 = phi i64 [ 0, %entry ], [ %tmp25, %bb2 ] ; <i64> [#uses=1]
%tmp25 = add i64 %i.019, 1 ; <i64> [#uses=2]
%tmp11 = load i32* @cl_options_count, align 4 ; <i32> [#uses=1]
%tmp12 = zext i32 %tmp11 to i64 ; <i64> [#uses=1]
%tmp13 = icmp ugt i64 %tmp12, %tmp25 ; <i1> [#uses=1]
br i1 %tmp13, label %bb2, label %bb6
bb6: ; preds = %bb2, %entry
ret void
}