test/Transforms/SROA/phi-and-select.ll

reference, declaration → definition
definition → references, declarations, derived classes, virtual overrides
reference to multiple definitions → definitions
unreferenced

; RUN: opt < %s -sroa -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64"

define i32 @test1() {
; CHECK-LABEL: @test1(
entry:
	%a = alloca [2 x i32]
; CHECK-NOT: alloca

  %a0 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
	store i32 0, i32* %a0
	store i32 1, i32* %a1
	%v0 = load i32, i32* %a0
	%v1 = load i32, i32* %a1
; CHECK-NOT: store
; CHECK-NOT: load

	%cond = icmp sle i32 %v0, %v1
	br i1 %cond, label %then, label %exit

then:
	br label %exit

exit:
	%phi = phi i32* [ %a1, %then ], [ %a0, %entry ]
; CHECK: phi i32 [ 1, %{{.*}} ], [ 0, %{{.*}} ]

	%result = load i32, i32* %phi
	ret i32 %result
}

define i32 @test2() {
; CHECK-LABEL: @test2(
entry:
	%a = alloca [2 x i32]
; CHECK-NOT: alloca

  %a0 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
	store i32 0, i32* %a0
	store i32 1, i32* %a1
	%v0 = load i32, i32* %a0
	%v1 = load i32, i32* %a1
; CHECK-NOT: store
; CHECK-NOT: load

	%cond = icmp sle i32 %v0, %v1
	%select = select i1 %cond, i32* %a1, i32* %a0
; CHECK: select i1 %{{.*}}, i32 1, i32 0

	%result = load i32, i32* %select
	ret i32 %result
}

; If bitcast isn't considered a safe phi/select use, the alloca
; remains as an array.
; FIXME: Why isn't this identical to test2?

; CHECK-LABEL: @test2_bitcast(
; CHECK: alloca i32
; CHECK-NEXT: alloca i32

; CHECK: %select = select i1 %cond, i32* %a.sroa.3, i32* %a.sroa.0
; CHECK-NEXT: %select.bc = bitcast i32* %select to float*
; CHECK-NEXT: %result = load float, float* %select.bc, align 4
define float @test2_bitcast() {
entry:
  %a = alloca [2 x i32]
  %a0 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
  store i32 0, i32* %a0
  store i32 1, i32* %a1
  %v0 = load i32, i32* %a0
  %v1 = load i32, i32* %a1
  %cond = icmp sle i32 %v0, %v1
  %select = select i1 %cond, i32* %a1, i32* %a0
  %select.bc = bitcast i32* %select to float*
  %result = load float, float* %select.bc
  ret float %result
}

; CHECK-LABEL: @test2_addrspacecast(
; CHECK: alloca i32
; CHECK-NEXT: alloca i32

; CHECK: %select = select i1 %cond, i32* %a.sroa.3, i32* %a.sroa.0
; CHECK-NEXT: %select.asc = addrspacecast i32* %select to i32 addrspace(1)*
; CHECK-NEXT: load i32, i32 addrspace(1)* %select.asc, align 4
define i32 @test2_addrspacecast() {
entry:
  %a = alloca [2 x i32]
  %a0 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
  store i32 0, i32* %a0
  store i32 1, i32* %a1
  %v0 = load i32, i32* %a0
  %v1 = load i32, i32* %a1
  %cond = icmp sle i32 %v0, %v1
  %select = select i1 %cond, i32* %a1, i32* %a0
  %select.asc = addrspacecast i32* %select to i32 addrspace(1)*
  %result = load i32, i32 addrspace(1)* %select.asc
  ret i32 %result
}

define i32 @test3(i32 %x) {
; CHECK-LABEL: @test3(
entry:
	%a = alloca [2 x i32]
; CHECK-NOT: alloca

  ; Note that we build redundant GEPs here to ensure that having different GEPs
  ; into the same alloca partation continues to work with PHI speculation. This
  ; was the underlying cause of PR13926.
  %a0 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a0b = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
  %a1b = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
	store i32 0, i32* %a0
	store i32 1, i32* %a1
; CHECK-NOT: store

  switch i32 %x, label %bb0 [ i32 1, label %bb1
                              i32 2, label %bb2
                              i32 3, label %bb3
                              i32 4, label %bb4
                              i32 5, label %bb5
                              i32 6, label %bb6
                              i32 7, label %bb7 ]

bb0:
	br label %exit
bb1:
	br label %exit
bb2:
	br label %exit
bb3:
	br label %exit
bb4:
	br label %exit
bb5:
	br label %exit
bb6:
	br label %exit
bb7:
	br label %exit

exit:
	%phi = phi i32* [ %a1, %bb0 ], [ %a0, %bb1 ], [ %a0, %bb2 ], [ %a1, %bb3 ],
                  [ %a1b, %bb4 ], [ %a0b, %bb5 ], [ %a0b, %bb6 ], [ %a1b, %bb7 ]
; CHECK: phi i32 [ 1, %{{.*}} ], [ 0, %{{.*}} ], [ 0, %{{.*}} ], [ 1, %{{.*}} ], [ 1, %{{.*}} ], [ 0, %{{.*}} ], [ 0, %{{.*}} ], [ 1, %{{.*}} ]

	%result = load i32, i32* %phi
	ret i32 %result
}

define i32 @test4() {
; CHECK-LABEL: @test4(
entry:
	%a = alloca [2 x i32]
; CHECK-NOT: alloca

  %a0 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 0
  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
	store i32 0, i32* %a0
	store i32 1, i32* %a1
	%v0 = load i32, i32* %a0
	%v1 = load i32, i32* %a1
; CHECK-NOT: store
; CHECK-NOT: load

	%cond = icmp sle i32 %v0, %v1
	%select = select i1 %cond, i32* %a0, i32* %a0
; CHECK-NOT: select

	%result = load i32, i32* %select
	ret i32 %result
; CHECK: ret i32 0
}

define i32 @test5(i32* %b) {
; CHECK-LABEL: @test5(
entry:
	%a = alloca [2 x i32]
; CHECK-NOT: alloca

  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
	store i32 1, i32* %a1
; CHECK-NOT: store

	%select = select i1 true, i32* %a1, i32* %b
; CHECK-NOT: select

	%result = load i32, i32* %select
; CHECK-NOT: load

	ret i32 %result
; CHECK: ret i32 1
}

declare void @f(i32*, i32*)

define i32 @test6(i32* %b) {
; CHECK-LABEL: @test6(
entry:
	%a = alloca [2 x i32]
  %c = alloca i32
; CHECK-NOT: alloca

  %a1 = getelementptr [2 x i32], [2 x i32]* %a, i64 0, i32 1
	store i32 1, i32* %a1

	%select = select i1 true, i32* %a1, i32* %b
	%select2 = select i1 false, i32* %a1, i32* %b
  %select3 = select i1 false, i32* %c, i32* %b
; CHECK: %[[select2:.*]] = select i1 false, i32* undef, i32* %b
; CHECK: %[[select3:.*]] = select i1 false, i32* undef, i32* %b

  ; Note, this would potentially escape the alloca pointer except for the
  ; constant folding of the select.
  call void @f(i32* %select2, i32* %select3)
; CHECK: call void @f(i32* %[[select2]], i32* %[[select3]])


	%result = load i32, i32* %select
; CHECK-NOT: load

  %dead = load i32, i32* %c

	ret i32 %result
; CHECK: ret i32 1
}

define i32 @test7() {
; CHECK-LABEL: @test7(
; CHECK-NOT: alloca

entry:
  %X = alloca i32
  br i1 undef, label %good, label %bad

good:
  %Y1 = getelementptr i32, i32* %X, i64 0
  store i32 0, i32* %Y1
  br label %exit

bad:
  %Y2 = getelementptr i32, i32* %X, i64 1
  store i32 0, i32* %Y2
  br label %exit

exit:
	%P = phi i32* [ %Y1, %good ], [ %Y2, %bad ]
; CHECK: %[[phi:.*]] = phi i32 [ 0, %good ],
  %Z2 = load i32, i32* %P
  ret i32 %Z2
; CHECK: ret i32 %[[phi]]
}

define i32 @test8(i32 %b, i32* %ptr) {
; Ensure that we rewrite allocas to the used type when that use is hidden by
; a PHI that can be speculated.
; CHECK-LABEL: @test8(
; CHECK-NOT: alloca
; CHECK-NOT: load
; CHECK: %[[value:.*]] = load i32, i32* %ptr
; CHECK-NOT: load
; CHECK: %[[result:.*]] = phi i32 [ undef, %else ], [ %[[value]], %then ]
; CHECK-NEXT: ret i32 %[[result]]

entry:
  %f = alloca float
  %test = icmp ne i32 %b, 0
  br i1 %test, label %then, label %else

then:
  br label %exit

else:
  %bitcast = bitcast float* %f to i32*
  br label %exit

exit:
  %phi = phi i32* [ %bitcast, %else ], [ %ptr, %then ]
  %loaded = load i32, i32* %phi, align 4
  ret i32 %loaded
}

define i32 @test9(i32 %b, i32* %ptr) {
; Same as @test8 but for a select rather than a PHI node.
; CHECK-LABEL: @test9(
; CHECK-NOT: alloca
; CHECK-NOT: load
; CHECK: %[[value:.*]] = load i32, i32* %ptr
; CHECK-NOT: load
; CHECK: %[[result:.*]] = select i1 %{{.*}}, i32 undef, i32 %[[value]]
; CHECK-NEXT: ret i32 %[[result]]

entry:
  %f = alloca float
  store i32 0, i32* %ptr
  %test = icmp ne i32 %b, 0
  %bitcast = bitcast float* %f to i32*
  %select = select i1 %test, i32* %bitcast, i32* %ptr
  %loaded = load i32, i32* %select, align 4
  ret i32 %loaded
}

define float @test10(i32 %b, float* %ptr) {
; Don't try to promote allocas which are not elligible for it even after
; rewriting due to the necessity of inserting bitcasts when speculating a PHI
; node.
; CHECK-LABEL: @test10(
; CHECK: %[[alloca:.*]] = alloca
; CHECK: %[[argvalue:.*]] = load float, float* %ptr
; CHECK: %[[cast:.*]] = bitcast double* %[[alloca]] to float*
; CHECK: %[[allocavalue:.*]] = load float, float* %[[cast]]
; CHECK: %[[result:.*]] = phi float [ %[[allocavalue]], %else ], [ %[[argvalue]], %then ]
; CHECK-NEXT: ret float %[[result]]

entry:
  %f = alloca double
  store double 0.0, double* %f
  %test = icmp ne i32 %b, 0
  br i1 %test, label %then, label %else

then:
  br label %exit

else:
  %bitcast = bitcast double* %f to float*
  br label %exit

exit:
  %phi = phi float* [ %bitcast, %else ], [ %ptr, %then ]
  %loaded = load float, float* %phi, align 4
  ret float %loaded
}

define float @test11(i32 %b, float* %ptr) {
; Same as @test10 but for a select rather than a PHI node.
; CHECK-LABEL: @test11(
; CHECK: %[[alloca:.*]] = alloca
; CHECK: %[[cast:.*]] = bitcast double* %[[alloca]] to float*
; CHECK: %[[allocavalue:.*]] = load float, float* %[[cast]]
; CHECK: %[[argvalue:.*]] = load float, float* %ptr
; CHECK: %[[result:.*]] = select i1 %{{.*}}, float %[[allocavalue]], float %[[argvalue]]
; CHECK-NEXT: ret float %[[result]]

entry:
  %f = alloca double
  store double 0.0, double* %f
  store float 0.0, float* %ptr
  %test = icmp ne i32 %b, 0
  %bitcast = bitcast double* %f to float*
  %select = select i1 %test, float* %bitcast, float* %ptr
  %loaded = load float, float* %select, align 4
  ret float %loaded
}

define i32 @test12(i32 %x, i32* %p) {
; Ensure we don't crash or fail to nuke dead selects of allocas if no load is
; never found.
; CHECK-LABEL: @test12(
; CHECK-NOT: alloca
; CHECK-NOT: select
; CHECK: ret i32 %x

entry:
  %a = alloca i32
  store i32 %x, i32* %a
  %dead = select i1 undef, i32* %a, i32* %p
  %load = load i32, i32* %a
  ret i32 %load
}

define i32 @test13(i32 %x, i32* %p) {
; Ensure we don't crash or fail to nuke dead phis of allocas if no load is ever
; found.
; CHECK-LABEL: @test13(
; CHECK-NOT: alloca
; CHECK-NOT: phi
; CHECK: ret i32 %x

entry:
  %a = alloca i32
  store i32 %x, i32* %a
  br label %loop

loop:
  %phi = phi i32* [ %p, %entry ], [ %a, %loop ]
  br i1 undef, label %loop, label %exit

exit:
  %load = load i32, i32* %a
  ret i32 %load
}

define i32 @test14(i1 %b1, i1 %b2, i32* %ptr) {
; Check for problems when there are both selects and phis and one is
; speculatable toward promotion but the other is not. That should block all of
; the speculation.
; CHECK-LABEL: @test14(
; CHECK: alloca
; CHECK: alloca
; CHECK: select
; CHECK: phi
; CHECK: phi
; CHECK: select
; CHECK: ret i32

entry:
  %f = alloca i32
  %g = alloca i32
  store i32 0, i32* %f
  store i32 0, i32* %g
  %f.select = select i1 %b1, i32* %f, i32* %ptr
  br i1 %b2, label %then, label %else

then:
  br label %exit

else:
  br label %exit

exit:
  %f.phi = phi i32* [ %f, %then ], [ %f.select, %else ]
  %g.phi = phi i32* [ %g, %then ], [ %ptr, %else ]
  %f.loaded = load i32, i32* %f.phi
  %g.select = select i1 %b1, i32* %g, i32* %g.phi
  %g.loaded = load i32, i32* %g.select
  %result = add i32 %f.loaded, %g.loaded
  ret i32 %result
}

define i32 @PR13905() {
; Check a pattern where we have a chain of dead phi nodes to ensure they are
; deleted and promotion can proceed.
; CHECK-LABEL: @PR13905(
; CHECK-NOT: alloca i32
; CHECK: ret i32 undef

entry:
  %h = alloca i32
  store i32 0, i32* %h
  br i1 undef, label %loop1, label %exit

loop1:
  %phi1 = phi i32* [ null, %entry ], [ %h, %loop1 ], [ %h, %loop2 ]
  br i1 undef, label %loop1, label %loop2

loop2:
  br i1 undef, label %loop1, label %exit

exit:
  %phi2 = phi i32* [ %phi1, %loop2 ], [ null, %entry ]
  ret i32 undef
}

define i32 @PR13906() {
; Another pattern which can lead to crashes due to failing to clear out dead
; PHI nodes or select nodes. This triggers subtly differently from the above
; cases because the PHI node is (recursively) alive, but the select is dead.
; CHECK-LABEL: @PR13906(
; CHECK-NOT: alloca

entry:
  %c = alloca i32
  store i32 0, i32* %c
  br label %for.cond

for.cond:
  %d.0 = phi i32* [ undef, %entry ], [ %c, %if.then ], [ %d.0, %for.cond ]
  br i1 undef, label %if.then, label %for.cond

if.then:
  %tmpcast.d.0 = select i1 undef, i32* %c, i32* %d.0
  br label %for.cond
}

define i64 @PR14132(i1 %flag) {
; CHECK-LABEL: @PR14132(
; Here we form a PHI-node by promoting the pointer alloca first, and then in
; order to promote the other two allocas, we speculate the load of the
; now-phi-node-pointer. In doing so we end up loading a 64-bit value from an i8
; alloca. While this is a bit dubious, we were asserting on trying to
; rewrite it. The trick is that the code using the value may carefully take
; steps to only use the not-undef bits, and so we need to at least loosely
; support this..
entry:
  %a = alloca i64, align 8
  %b = alloca i8, align 8
  %ptr = alloca i64*, align 8
; CHECK-NOT: alloca

  %ptr.cast = bitcast i64** %ptr to i8**
  store i64 0, i64* %a, align 8
  store i8 1, i8* %b, align 8
  store i64* %a, i64** %ptr, align 8
  br i1 %flag, label %if.then, label %if.end

if.then:
  store i8* %b, i8** %ptr.cast, align 8
  br label %if.end
; CHECK-NOT: store
; CHECK: %[[ext:.*]] = zext i8 1 to i64

if.end:
  %tmp = load i64*, i64** %ptr, align 8
  %result = load i64, i64* %tmp, align 8
; CHECK-NOT: load
; CHECK: %[[result:.*]] = phi i64 [ %[[ext]], %if.then ], [ 0, %entry ]

  ret i64 %result
; CHECK-NEXT: ret i64 %[[result]]
}

define float @PR16687(i64 %x, i1 %flag) {
; CHECK-LABEL: @PR16687(
; Check that even when we try to speculate the same phi twice (in two slices)
; on an otherwise promotable construct, we don't get ahead of ourselves and try
; to promote one of the slices prior to speculating it.

entry:
  %a = alloca i64, align 8
  store i64 %x, i64* %a
  br i1 %flag, label %then, label %else
; CHECK-NOT: alloca
; CHECK-NOT: store
; CHECK: %[[lo:.*]] = trunc i64 %x to i32
; CHECK: %[[shift:.*]] = lshr i64 %x, 32
; CHECK: %[[hi:.*]] = trunc i64 %[[shift]] to i32

then:
  %a.f = bitcast i64* %a to float*
  br label %end
; CHECK: %[[lo_cast:.*]] = bitcast i32 %[[lo]] to float

else:
  %a.raw = bitcast i64* %a to i8*
  %a.raw.4 = getelementptr i8, i8* %a.raw, i64 4
  %a.raw.4.f = bitcast i8* %a.raw.4 to float*
  br label %end
; CHECK: %[[hi_cast:.*]] = bitcast i32 %[[hi]] to float

end:
  %a.phi.f = phi float* [ %a.f, %then ], [ %a.raw.4.f, %else ]
  %f = load float, float* %a.phi.f
  ret float %f
; CHECK: %[[phi:.*]] = phi float [ %[[lo_cast]], %then ], [ %[[hi_cast]], %else ]
; CHECK-NOT: load
; CHECK: ret float %[[phi]]
}

; Verifies we fixed PR20425. We should be able to promote all alloca's to
; registers in this test.
;
; %0 = slice
; %1 = slice
; %2 = phi(%0, %1) // == slice
define float @simplify_phi_nodes_that_equal_slice(i1 %cond, float* %temp) {
; CHECK-LABEL: @simplify_phi_nodes_that_equal_slice(
entry:
  %arr = alloca [4 x float], align 4
; CHECK-NOT: alloca
  br i1 %cond, label %then, label %else

then:
  %0 = getelementptr inbounds [4 x float], [4 x float]* %arr, i64 0, i64 3
  store float 1.000000e+00, float* %0, align 4
  br label %merge

else:
  %1 = getelementptr inbounds [4 x float], [4 x float]* %arr, i64 0, i64 3
  store float 2.000000e+00, float* %1, align 4
  br label %merge

merge:
  %2 = phi float* [ %0, %then ], [ %1, %else ]
  store float 0.000000e+00, float* %temp, align 4
  %3 = load float, float* %2, align 4
  ret float %3
}

; A slightly complicated example for PR20425.
;
; %0 = slice
; %1 = phi(%0) // == slice
; %2 = slice
; %3 = phi(%1, %2) // == slice
define float @simplify_phi_nodes_that_equal_slice_2(i1 %cond, float* %temp) {
; CHECK-LABEL: @simplify_phi_nodes_that_equal_slice_2(
entry:
  %arr = alloca [4 x float], align 4
; CHECK-NOT: alloca
  br i1 %cond, label %then, label %else

then:
  %0 = getelementptr inbounds [4 x float], [4 x float]* %arr, i64 0, i64 3
  store float 1.000000e+00, float* %0, align 4
  br label %then2

then2:
  %1 = phi float* [ %0, %then ]
  store float 2.000000e+00, float* %1, align 4
  br label %merge

else:
  %2 = getelementptr inbounds [4 x float], [4 x float]* %arr, i64 0, i64 3
  store float 3.000000e+00, float* %2, align 4
  br label %merge

merge:
  %3 = phi float* [ %1, %then2 ], [ %2, %else ]
  store float 0.000000e+00, float* %temp, align 4
  %4 = load float, float* %3, align 4
  ret float %4
}

%struct.S = type { i32 }

; Verifies we fixed PR20822. We have a foldable PHI feeding a speculatable PHI
; which requires the rewriting of the speculated PHI to handle insertion
; when the incoming pointer is itself from a PHI node. We would previously
; insert a bitcast instruction *before* a PHI, producing an invalid module;
; make sure we insert *after* the first non-PHI instruction.
define void @PR20822() {
; CHECK-LABEL: @PR20822(
entry:
  %f = alloca %struct.S, align 4
; CHECK: %[[alloca:.*]] = alloca
  br i1 undef, label %if.end, label %for.cond

for.cond:                                         ; preds = %for.cond, %entry
  br label %if.end

if.end:                                           ; preds = %for.cond, %entry
  %f2 = phi %struct.S* [ %f, %entry ], [ %f, %for.cond ]
; CHECK: phi i32
; CHECK: %[[cast:.*]] = bitcast i32* %[[alloca]] to %struct.S*
  phi i32 [ undef, %entry ], [ undef, %for.cond ]
  br i1 undef, label %if.then5, label %if.then2

if.then2:                                         ; preds = %if.end
  br label %if.then5

if.then5:                                         ; preds = %if.then2, %if.end
  %f1 = phi %struct.S* [ undef, %if.then2 ], [ %f2, %if.end ]
; CHECK: phi {{.*}} %[[cast]]
  store %struct.S undef, %struct.S* %f1, align 4
  ret void
}

define i32 @phi_align(i32* %z) {
; CHECK-LABEL: @phi_align(
entry:
  %a = alloca [8 x i8], align 8
; CHECK: alloca [7 x i8]

  %a0x = getelementptr [8 x i8], [8 x i8]* %a, i64 0, i32 1
  %a0 = bitcast i8* %a0x to i32*
  %a1x = getelementptr [8 x i8], [8 x i8]* %a, i64 0, i32 4
  %a1 = bitcast i8* %a1x to i32*
; CHECK: store i32 0, {{.*}}, align 1
  store i32 0, i32* %a0, align 1
; CHECK: store i32 1, {{.*}}, align 1
  store i32 1, i32* %a1, align 4
; CHECK: load {{.*}}, align 1
  %v0 = load i32, i32* %a0, align 1
; CHECK: load {{.*}}, align 1
  %v1 = load i32, i32* %a1, align 4
  %cond = icmp sle i32 %v0, %v1
  br i1 %cond, label %then, label %exit

then:
  br label %exit

exit:
; CHECK: %phi = phi i32* [ {{.*}}, %then ], [ %z, %entry ]
; CHECK-NEXT: %result = load i32, i32* %phi, align 1
  %phi = phi i32* [ %a1, %then ], [ %z, %entry ]
  %result = load i32, i32* %phi, align 4
  ret i32 %result
}

; Don't speculate a load based on an earlier volatile operation.
define i8 @volatile_select(i8* %p, i1 %b) {
; CHECK-LABEL: @volatile_select(
; CHECK: select i1 %b, i8* %p, i8* %p2
  %p2 = alloca i8
  store i8 0, i8* %p2
  store volatile i8 0, i8* %p
  %px = select i1 %b, i8* %p, i8* %p2
  %v2 = load i8, i8* %px
  ret i8 %v2
}