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llvm-mirror/test/CodeGen/X86/pseudo_cmov_lower2.ll
Dehao Chen 5673833207 Lower consecutive select instructions correctly.
Summary: If consecutive select instructions are lowered separately in CGP, it will introduce redundant condition check and branches that cannot be removed by later optimization phases. This patch lowers all consecutive select instructions at the same to to avoid inefficent code as demonstrated in https://llvm.org/bugs/show_bug.cgi?id=29095

Reviewers: davidxl

Subscribers: vsk, llvm-commits

Differential Revision: https://reviews.llvm.org/D24147

llvm-svn: 281252
2016-09-12 20:23:28 +00:00

145 lines
5.0 KiB
LLVM

; RUN: llc < %s -mtriple=x86_64-linux-gnu -o - | FileCheck %s
; This test checks that only a single jae gets generated in the final code
; for lowering the CMOV pseudos that get created for this IR. The tricky part
; of this test is that it tests the special PHI operand rewriting code in
; X86TargetLowering::EmitLoweredSelect.
;
; CHECK-LABEL: foo1:
; CHECK: jae
; CHECK-NOT: jae
define double @foo1(float %p1, double %p2, double %p3) nounwind {
entry:
%c1 = fcmp oge float %p1, 0.000000e+00
%d0 = fadd double %p2, 1.25e0
%d1 = fadd double %p3, 1.25e0
%d2 = select i1 %c1, double %d0, double %d1
%d3 = select i1 %c1, double %d2, double %p2
%d4 = select i1 %c1, double %d3, double %p3
%d5 = fsub double %d2, %d3
%d6 = fadd double %d5, %d4
ret double %d6
}
; This test checks that only a single jae gets generated in the final code
; for lowering the CMOV pseudos that get created for this IR. The tricky part
; of this test is that it tests the special PHI operand rewriting code in
; X86TargetLowering::EmitLoweredSelect.
;
; CHECK-LABEL: foo2:
; CHECK: jae
; CHECK-NOT: jae
define double @foo2(float %p1, double %p2, double %p3) nounwind {
entry:
%c1 = fcmp oge float %p1, 0.000000e+00
%d0 = fadd double %p2, 1.25e0
%d1 = fadd double %p3, 1.25e0
%d2 = select i1 %c1, double %d0, double %d1
%d3 = select i1 %c1, double %p2, double %d2
%d4 = select i1 %c1, double %p3, double %d3
%d5 = fsub double %d2, %d3
%d6 = fadd double %d5, %d4
ret double %d6
}
; This test checks that only a single js gets generated in the final code
; for lowering the CMOV pseudos that get created for this IR. The tricky part
; of this test is that it tests the special PHI operand rewriting code in
; X86TargetLowering::EmitLoweredSelect. It also tests to make sure all
; the operands of the resulting instructions are from the proper places.
;
; CHECK-LABEL: foo3:
; CHECK: js
; CHECK-NOT: js
; CHECK-LABEL: # BB#1:
; CHECK-DAG: movapd %xmm2, %xmm1
; CHECK-DAG: movapd %xmm2, %xmm0
; CHECK-LABEL:.LBB2_2:
; CHECK: divsd %xmm1, %xmm0
; CHECK: ret
define double @foo3(i32 %p1, double %p2, double %p3,
double %p4, double %p5) nounwind {
entry:
%c1 = icmp slt i32 %p1, 0
%d2 = select i1 %c1, double %p2, double %p3
%d3 = select i1 %c1, double %p3, double %p4
%d4 = select i1 %c1, double %d2, double %d3
%d5 = fdiv double %d4, %d3
ret double %d5
}
; This test checks that only a single js gets generated in the final code
; for lowering the CMOV pseudos that get created for this IR. The tricky part
; of this test is that it tests the special PHI operand rewriting code in
; X86TargetLowering::EmitLoweredSelect. It also tests to make sure all
; the operands of the resulting instructions are from the proper places
; when the "opposite condition" handling code in the compiler is used.
; This should be the same code as foo3 above, because we use the opposite
; condition code in the second two selects, but we also swap the operands
; of the selects to give the same actual computation.
;
; CHECK-LABEL: foo4:
; CHECK: js
; CHECK-NOT: js
; CHECK-LABEL: # BB#1:
; CHECK-DAG: movapd %xmm2, %xmm1
; CHECK-DAG: movapd %xmm2, %xmm0
; CHECK-LABEL:.LBB3_2:
; CHECK: divsd %xmm1, %xmm0
; CHECK: ret
define double @foo4(i32 %p1, double %p2, double %p3,
double %p4, double %p5) nounwind {
entry:
%c1 = icmp slt i32 %p1, 0
%d2 = select i1 %c1, double %p2, double %p3
%c2 = icmp sge i32 %p1, 0
%d3 = select i1 %c2, double %p4, double %p3
%d4 = select i1 %c2, double %d3, double %d2
%d5 = fdiv double %d4, %d3
ret double %d5
}
; This test checks that only a single jae gets generated in the final code
; for lowering the CMOV pseudos that get created for this IR. The tricky part
; of this test is that it tests the special code in CodeGenPrepare.
;
; CHECK-LABEL: foo5:
; CHECK: jae
; CHECK-NOT: jae
define double @foo5(float %p1, double %p2, double %p3) nounwind {
entry:
%c1 = fcmp oge float %p1, 0.000000e+00
%d0 = fadd double %p2, 1.25e0
%d1 = fadd double %p3, 1.25e0
%d2 = select i1 %c1, double %d0, double %d1, !prof !0
%d3 = select i1 %c1, double %d2, double %p2, !prof !0
%d4 = select i1 %c1, double %d3, double %p3, !prof !0
%d5 = fsub double %d2, %d3
%d6 = fadd double %d5, %d4
ret double %d6
}
; We should expand select instructions into 3 conditional branches as their
; condtions are different.
;
; CHECK-LABEL: foo6:
; CHECK: jae
; CHECK: jae
; CHECK: jae
define double @foo6(float %p1, double %p2, double %p3) nounwind {
entry:
%c1 = fcmp oge float %p1, 0.000000e+00
%c2 = fcmp oge float %p1, 1.000000e+00
%c3 = fcmp oge float %p1, 2.000000e+00
%d0 = fadd double %p2, 1.25e0
%d1 = fadd double %p3, 1.25e0
%d2 = select i1 %c1, double %d0, double %d1, !prof !0
%d3 = select i1 %c2, double %d2, double %p2, !prof !0
%d4 = select i1 %c3, double %d3, double %p3, !prof !0
%d5 = fsub double %d2, %d3
%d6 = fadd double %d5, %d4
ret double %d6
}
!0 = !{!"branch_weights", i32 1, i32 2000}