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|   | # RUN: llc -march=amdgcn -run-pass detect-dead-lanes -o - %s | FileCheck %s | ||
|  | ... | ||
|  | --- | ||
|  | # Combined use/def transfer check, the basics. | ||
|  | # CHECK-LABEL: name: test0 | ||
|  | # CHECK: S_NOP 0, implicit-def %0 | ||
|  | # CHECK: S_NOP 0, implicit-def %1 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %2 | ||
|  | # CHECK: %3:sreg_128 = REG_SEQUENCE %0,  %subreg.sub0, %1,  %subreg.sub1, undef %2, %subreg.sub3 | ||
|  | # CHECK: S_NOP 0, implicit %3.sub0 | ||
|  | # CHECK: S_NOP 0, implicit %3.sub1 | ||
|  | # CHECK: S_NOP 0, implicit undef %3.sub2 | ||
|  | # CHECK: %4:sreg_64 = COPY %3.sub0_sub1 | ||
|  | # CHECK: %5:sreg_64 = COPY undef %3.sub2_sub3 | ||
|  | # CHECK: S_NOP 0, implicit %4.sub0 | ||
|  | # CHECK: S_NOP 0, implicit %4.sub1 | ||
|  | # CHECK: S_NOP 0, implicit undef %5.sub0 | ||
|  | name: test0 | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_32_xm0 } | ||
|  |   - { id: 1, class: sreg_32_xm0 } | ||
|  |   - { id: 2, class: sreg_32_xm0 } | ||
|  |   - { id: 3, class: sreg_128 } | ||
|  |   - { id: 4, class: sreg_64 } | ||
|  |   - { id: 5, class: sreg_64 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     S_NOP 0, implicit-def %1 | ||
|  |     S_NOP 0, implicit-def %2 | ||
|  |     %3 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub3 | ||
|  |     S_NOP 0, implicit %3.sub0 | ||
|  |     S_NOP 0, implicit %3.sub1 | ||
|  |     S_NOP 0, implicit %3.sub2 | ||
|  |     %4 = COPY %3.sub0_sub1 | ||
|  |     %5 = COPY %3.sub2_sub3 | ||
|  |     S_NOP 0, implicit %4.sub0 | ||
|  |     S_NOP 0, implicit %4.sub1 | ||
|  |     S_NOP 0, implicit %5.sub0 | ||
|  | ... | ||
|  | --- | ||
|  | # Check defined lanes transfer; Includes checking for some special cases like | ||
|  | # undef operands or IMPLICIT_DEF definitions. | ||
|  | # CHECK-LABEL: name: test1 | ||
|  | # CHECK: %0:sreg_128 = REG_SEQUENCE %sgpr0, %subreg.sub0, %sgpr0, %subreg.sub2 | ||
|  | # CHECK: %1:sreg_128 = INSERT_SUBREG %0, %sgpr1,  %subreg.sub3 | ||
|  | # CHECK: %2:sreg_64 = INSERT_SUBREG %0.sub2_sub3, %sgpr42,  %subreg.sub0 | ||
|  | # CHECK: S_NOP 0, implicit %1.sub0 | ||
|  | # CHECK: S_NOP 0, implicit undef %1.sub1 | ||
|  | # CHECK: S_NOP 0, implicit %1.sub2 | ||
|  | # CHECK: S_NOP 0, implicit %1.sub3 | ||
|  | # CHECK: S_NOP 0, implicit %2.sub0 | ||
|  | # CHECK: S_NOP 0, implicit undef %2.sub1 | ||
|  | 
 | ||
|  | # CHECK: %3:sreg_32_xm0 = IMPLICIT_DEF | ||
|  | # CHECK: %4:sreg_128 = INSERT_SUBREG %0, undef %3, %subreg.sub0 | ||
|  | # CHECK: S_NOP 0, implicit undef %4.sub0 | ||
|  | # CHECK: S_NOP 0, implicit undef %4.sub1 | ||
|  | # CHECK: S_NOP 0, implicit %4.sub2 | ||
|  | # CHECK: S_NOP 0, implicit undef %4.sub3 | ||
|  | 
 | ||
|  | # CHECK: %5:sreg_64 = EXTRACT_SUBREG %0, %subreg.sub0_sub1 | ||
|  | # CHECK: %6:sreg_32_xm0 = EXTRACT_SUBREG %5, %subreg.sub0 | ||
|  | # CHECK: %7:sreg_32_xm0 = EXTRACT_SUBREG %5, %subreg.sub1 | ||
|  | # CHECK: S_NOP 0, implicit %5 | ||
|  | # CHECK: S_NOP 0, implicit %6 | ||
|  | # CHECK: S_NOP 0, implicit undef %7 | ||
|  | 
 | ||
|  | # CHECK: %8:sreg_64 = IMPLICIT_DEF | ||
|  | # CHECK: %9:sreg_32_xm0 = EXTRACT_SUBREG undef %8, %subreg.sub1 | ||
|  | # CHECK: S_NOP 0, implicit undef %9 | ||
|  | 
 | ||
|  | # CHECK: %10:sreg_128 = EXTRACT_SUBREG undef %0, %subreg.sub2_sub3 | ||
|  | # CHECK: S_NOP 0, implicit undef %10 | ||
|  | name: test1 | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_128 } | ||
|  |   - { id: 1, class: sreg_128 } | ||
|  |   - { id: 2, class: sreg_64 } | ||
|  |   - { id: 3, class: sreg_32_xm0 } | ||
|  |   - { id: 4, class: sreg_128 } | ||
|  |   - { id: 5, class: sreg_64 } | ||
|  |   - { id: 6, class: sreg_32_xm0 } | ||
|  |   - { id: 7, class: sreg_32_xm0 } | ||
|  |   - { id: 8, class: sreg_64 } | ||
|  |   - { id: 9, class: sreg_32_xm0 } | ||
|  |   - { id: 10, class: sreg_128 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     %0 = REG_SEQUENCE %sgpr0, %subreg.sub0, %sgpr0, %subreg.sub2 | ||
|  |     %1 = INSERT_SUBREG %0, %sgpr1, %subreg.sub3 | ||
|  |     %2 = INSERT_SUBREG %0.sub2_sub3, %sgpr42, %subreg.sub0 | ||
|  |     S_NOP 0, implicit %1.sub0 | ||
|  |     S_NOP 0, implicit %1.sub1 | ||
|  |     S_NOP 0, implicit %1.sub2 | ||
|  |     S_NOP 0, implicit %1.sub3 | ||
|  |     S_NOP 0, implicit %2.sub0 | ||
|  |     S_NOP 0, implicit %2.sub1 | ||
|  | 
 | ||
|  |     %3 = IMPLICIT_DEF | ||
|  |     %4 = INSERT_SUBREG %0, %3, %subreg.sub0 | ||
|  |     S_NOP 0, implicit %4.sub0 | ||
|  |     S_NOP 0, implicit %4.sub1 | ||
|  |     S_NOP 0, implicit %4.sub2 | ||
|  |     S_NOP 0, implicit %4.sub3 | ||
|  | 
 | ||
|  |     %5 = EXTRACT_SUBREG %0, %subreg.sub0_sub1 | ||
|  |     %6 = EXTRACT_SUBREG %5, %subreg.sub0 | ||
|  |     %7 = EXTRACT_SUBREG %5, %subreg.sub1 | ||
|  |     S_NOP 0, implicit %5 | ||
|  |     S_NOP 0, implicit %6 | ||
|  |     S_NOP 0, implicit %7 | ||
|  | 
 | ||
|  |     %8 = IMPLICIT_DEF | ||
|  |     %9 = EXTRACT_SUBREG %8, %subreg.sub1 | ||
|  |     S_NOP 0, implicit %9 | ||
|  | 
 | ||
|  |     %10 = EXTRACT_SUBREG undef %0, %subreg.sub2_sub3 | ||
|  |     S_NOP 0, implicit %10 | ||
|  | ... | ||
|  | --- | ||
|  | # Check used lanes transfer; Includes checking for some special cases like | ||
|  | # undef operands. | ||
|  | # CHECK-LABEL: name: test2 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %0 | ||
|  | # CHECK: S_NOP 0, implicit-def %1 | ||
|  | # CHECK: S_NOP 0, implicit-def %2 | ||
|  | # CHECK: %3:sreg_128 = REG_SEQUENCE undef %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2_sub3 | ||
|  | # CHECK: S_NOP 0, implicit %3.sub1 | ||
|  | # CHECK: S_NOP 0, implicit %3.sub3 | ||
|  | 
 | ||
|  | # CHECK: S_NOP 0, implicit-def %4 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %5 | ||
|  | # CHECK: %6:sreg_64 = REG_SEQUENCE %4, %subreg.sub0, undef %5, %subreg.sub1 | ||
|  | # CHECK: S_NOP 0, implicit %6 | ||
|  | 
 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %7 | ||
|  | # CHECK: S_NOP 0, implicit-def %8 | ||
|  | # CHECK: %9:sreg_128 = INSERT_SUBREG undef %7, %8, %subreg.sub2_sub3 | ||
|  | # CHECK: S_NOP 0, implicit %9.sub2 | ||
|  | 
 | ||
|  | # CHECK: S_NOP 0, implicit-def %10 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %11 | ||
|  | # CHECK: %12:sreg_128 = INSERT_SUBREG %10, undef %11, %subreg.sub0_sub1 | ||
|  | # CHECK: S_NOP 0, implicit %12.sub3 | ||
|  | 
 | ||
|  | # CHECK: S_NOP 0, implicit-def %13 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %14 | ||
|  | # CHECK: %15:sreg_128 = REG_SEQUENCE %13, %subreg.sub0_sub1, undef %14, %subreg.sub2_sub3 | ||
|  | # CHECK: %16:sreg_64 = EXTRACT_SUBREG %15, %subreg.sub0_sub1 | ||
|  | # CHECK: S_NOP 0, implicit %16.sub1 | ||
|  | 
 | ||
|  | name: test2 | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_32_xm0 } | ||
|  |   - { id: 1, class: sreg_32_xm0 } | ||
|  |   - { id: 2, class: sreg_64 } | ||
|  |   - { id: 3, class: sreg_128 } | ||
|  |   - { id: 4, class: sreg_32_xm0 } | ||
|  |   - { id: 5, class: sreg_32_xm0 } | ||
|  |   - { id: 6, class: sreg_64 } | ||
|  |   - { id: 7, class: sreg_128 } | ||
|  |   - { id: 8, class: sreg_64 } | ||
|  |   - { id: 9, class: sreg_128 } | ||
|  |   - { id: 10, class: sreg_128 } | ||
|  |   - { id: 11, class: sreg_64 } | ||
|  |   - { id: 12, class: sreg_128 } | ||
|  |   - { id: 13, class: sreg_64 } | ||
|  |   - { id: 14, class: sreg_64 } | ||
|  |   - { id: 15, class: sreg_128 } | ||
|  |   - { id: 16, class: sreg_64 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     S_NOP 0, implicit-def %1 | ||
|  |     S_NOP 0, implicit-def %2 | ||
|  |     %3 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2_sub3 | ||
|  |     S_NOP 0, implicit %3.sub1 | ||
|  |     S_NOP 0, implicit %3.sub3 | ||
|  | 
 | ||
|  |     S_NOP 0, implicit-def %4 | ||
|  |     S_NOP 0, implicit-def %5 | ||
|  |     %6 = REG_SEQUENCE %4, %subreg.sub0, undef %5, %subreg.sub1 | ||
|  |     S_NOP 0, implicit %6 | ||
|  | 
 | ||
|  |     S_NOP 0, implicit-def %7 | ||
|  |     S_NOP 0, implicit-def %8 | ||
|  |     %9 = INSERT_SUBREG %7, %8, %subreg.sub2_sub3 | ||
|  |     S_NOP 0, implicit %9.sub2 | ||
|  | 
 | ||
|  |     S_NOP 0, implicit-def %10 | ||
|  |     S_NOP 0, implicit-def %11 | ||
|  |     %12 = INSERT_SUBREG %10, %11, %subreg.sub0_sub1 | ||
|  |     S_NOP 0, implicit %12.sub3 | ||
|  | 
 | ||
|  |     S_NOP 0, implicit-def %13 | ||
|  |     S_NOP 0, implicit-def %14 | ||
|  |     %15 = REG_SEQUENCE %13, %subreg.sub0_sub1, %14, %subreg.sub2_sub3 | ||
|  |     %16 = EXTRACT_SUBREG %15, %subreg.sub0_sub1 | ||
|  |     S_NOP 0, implicit %16.sub1 | ||
|  | ... | ||
|  | --- | ||
|  | # Check that copies to physregs use all lanes, copies from physregs define all | ||
|  | # lanes. So we should not get a dead/undef flag here. | ||
|  | # CHECK-LABEL: name: test3 | ||
|  | # CHECK: S_NOP 0, implicit-def %0 | ||
|  | # CHECK: %vcc = COPY %0 | ||
|  | # CHECK: %1:sreg_64 = COPY %vcc | ||
|  | # CHECK: S_NOP 0, implicit %1 | ||
|  | name: test3 | ||
|  | tracksRegLiveness: true | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_64 } | ||
|  |   - { id: 1, class: sreg_64 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     %vcc = COPY %0 | ||
|  | 
 | ||
|  |     %1 = COPY %vcc | ||
|  |     S_NOP 0, implicit %1 | ||
|  | ... | ||
|  | --- | ||
|  | # Check that implicit-def/kill do not count as def/uses. | ||
|  | # CHECK-LABEL: name: test4 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %0 | ||
|  | # CHECK: KILL undef %0 | ||
|  | # CHECK: %1:sreg_64 = IMPLICIT_DEF | ||
|  | # CHECK: S_NOP 0, implicit undef %1 | ||
|  | name: test4 | ||
|  | tracksRegLiveness: true | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_64 } | ||
|  |   - { id: 1, class: sreg_64 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     KILL %0 | ||
|  | 
 | ||
|  |     %1 = IMPLICIT_DEF | ||
|  |     S_NOP 0, implicit %1 | ||
|  | ... | ||
|  | --- | ||
|  | # Check that unused inputs are marked as undef, even if the vreg itself is | ||
|  | # used. | ||
|  | # CHECK-LABEL: name: test5 | ||
|  | # CHECK: S_NOP 0, implicit-def %0 | ||
|  | # CHECK: %1:sreg_64 = REG_SEQUENCE undef %0, %subreg.sub0, %0, %subreg.sub1 | ||
|  | # CHECK: S_NOP 0, implicit %1.sub1 | ||
|  | name: test5 | ||
|  | tracksRegLiveness: true | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_32_xm0 } | ||
|  |   - { id: 1, class: sreg_64 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     %1 = REG_SEQUENCE %0, %subreg.sub0, %0, %subreg.sub1 | ||
|  |     S_NOP 0, implicit %1.sub1 | ||
|  | ... | ||
|  | --- | ||
|  | # Check "optimistic" dataflow fixpoint in phi-loops. | ||
|  | # CHECK-LABEL: name: loop0 | ||
|  | # CHECK: bb.0: | ||
|  | # CHECK: S_NOP 0, implicit-def %0 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %1 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %2 | ||
|  | # CHECK: %3:sreg_128 = REG_SEQUENCE %0,  %subreg.sub0, undef %1,  %subreg.sub1, undef %2,  %subreg.sub2 | ||
|  | 
 | ||
|  | # CHECK: bb.1: | ||
|  | # CHECK: %4:sreg_128 = PHI %3, %bb.0, %5, %bb.1 | ||
|  | 
 | ||
|  | # CHECK: bb.2: | ||
|  | # CHECK:   S_NOP 0, implicit %4.sub0 | ||
|  | # CHECK:   S_NOP 0, implicit undef %4.sub3 | ||
|  | name: loop0 | ||
|  | tracksRegLiveness: true | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_32_xm0 } | ||
|  |   - { id: 1, class: sreg_32_xm0 } | ||
|  |   - { id: 2, class: sreg_32_xm0 } | ||
|  |   - { id: 3, class: sreg_128 } | ||
|  |   - { id: 4, class: sreg_128 } | ||
|  |   - { id: 5, class: sreg_128 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     S_NOP 0, implicit-def %1 | ||
|  |     S_NOP 0, implicit-def %2 | ||
|  |     %3 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2 | ||
|  |     S_BRANCH %bb.1 | ||
|  | 
 | ||
|  |   bb.1: | ||
|  |     %4 = PHI %3, %bb.0, %5, %bb.1 | ||
|  | 
 | ||
|  |     ; let's swiffle some lanes around for fun... | ||
|  |     %5 = REG_SEQUENCE %4.sub0, %subreg.sub0, %4.sub2, %subreg.sub1, %4.sub1, %subreg.sub2, %4.sub3, %subreg.sub3 | ||
|  | 
 | ||
|  |     S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc | ||
|  |     S_BRANCH %bb.2 | ||
|  | 
 | ||
|  |   bb.2: | ||
|  |     S_NOP 0, implicit %4.sub0 | ||
|  |     S_NOP 0, implicit %4.sub3 | ||
|  | ... | ||
|  | --- | ||
|  | # Check a loop that needs to be traversed multiple times to reach the fixpoint | ||
|  | # for the used lanes. The example reads sub3 lane at the end, however with each | ||
|  | # loop iteration we should get 1 more lane marked as we cycles the sublanes | ||
|  | # along. Sublanes sub0, sub1 and sub3 are rotate in the loop so only sub2 | ||
|  | # should be dead. | ||
|  | # CHECK-LABEL: name: loop1 | ||
|  | # CHECK: bb.0: | ||
|  | # CHECK: S_NOP 0, implicit-def %0 | ||
|  | # CHECK: S_NOP 0, implicit-def %1 | ||
|  | # CHECK: S_NOP 0, implicit-def dead %2 | ||
|  | # CHECK: S_NOP 0, implicit-def %3 | ||
|  | # CHECK: %4:sreg_128 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, undef %2, %subreg.sub2, %3, %subreg.sub3 | ||
|  | 
 | ||
|  | # CHECK: bb.1: | ||
|  | # CHECK: %5:sreg_128 = PHI %4, %bb.0, %6, %bb.1 | ||
|  | 
 | ||
|  | # CHECK: %6:sreg_128 = REG_SEQUENCE %5.sub1, %subreg.sub0, %5.sub3, %subreg.sub1, undef %5.sub2, %subreg.sub2, %5.sub0, %subreg.sub3 | ||
|  | 
 | ||
|  | # CHECK: bb.2: | ||
|  | # CHECK:   S_NOP 0, implicit %6.sub3 | ||
|  | name: loop1 | ||
|  | tracksRegLiveness: true | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_32_xm0 } | ||
|  |   - { id: 1, class: sreg_32_xm0 } | ||
|  |   - { id: 2, class: sreg_32_xm0 } | ||
|  |   - { id: 3, class: sreg_32_xm0 } | ||
|  |   - { id: 4, class: sreg_128 } | ||
|  |   - { id: 5, class: sreg_128 } | ||
|  |   - { id: 6, class: sreg_128 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     S_NOP 0, implicit-def %1 | ||
|  |     S_NOP 0, implicit-def dead %2 | ||
|  |     S_NOP 0, implicit-def %3 | ||
|  |     %4 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2, %3, %subreg.sub3 | ||
|  |     S_BRANCH %bb.1 | ||
|  | 
 | ||
|  |   bb.1: | ||
|  |     %5 = PHI %4, %bb.0, %6, %bb.1 | ||
|  | 
 | ||
|  |     ; rotate lanes, but skip sub2 lane... | ||
|  |     %6 = REG_SEQUENCE %5.sub1, %subreg.sub0, %5.sub3, %subreg.sub1, %5.sub2, %subreg.sub2, %5.sub0, %subreg.sub3 | ||
|  | 
 | ||
|  |     S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc | ||
|  |     S_BRANCH %bb.2 | ||
|  | 
 | ||
|  |   bb.2: | ||
|  |     S_NOP 0, implicit %6.sub3 | ||
|  | ... | ||
|  | --- | ||
|  | # Similar to loop1 test, but check for fixpoint of defined lanes. | ||
|  | # Lanes are rotate between sub0, sub2, sub3 so only sub1 should be dead/undef. | ||
|  | # CHECK-LABEL: name: loop2 | ||
|  | # CHECK: bb.0: | ||
|  | # CHECK: S_NOP 0, implicit-def %0 | ||
|  | # CHECK: %1:sreg_128 = REG_SEQUENCE %0, %subreg.sub0 | ||
|  | 
 | ||
|  | # CHECK: bb.1: | ||
|  | # CHECK: %2:sreg_128 = PHI %1, %bb.0, %3, %bb.1 | ||
|  | 
 | ||
|  | # CHECK: %3:sreg_128 = REG_SEQUENCE %2.sub3, %subreg.sub0, undef %2.sub1, %subreg.sub1, %2.sub0, %subreg.sub2, %2.sub2, %subreg.sub3 | ||
|  | 
 | ||
|  | # CHECK: bb.2: | ||
|  | # CHECK:   S_NOP 0, implicit %2.sub0 | ||
|  | # CHECK:   S_NOP 0, implicit undef %2.sub1 | ||
|  | # CHECK:   S_NOP 0, implicit %2.sub2 | ||
|  | # CHECK:   S_NOP 0, implicit %2.sub3 | ||
|  | name: loop2 | ||
|  | tracksRegLiveness: true | ||
|  | registers: | ||
|  |   - { id: 0, class: sreg_32_xm0 } | ||
|  |   - { id: 1, class: sreg_128 } | ||
|  |   - { id: 2, class: sreg_128 } | ||
|  |   - { id: 3, class: sreg_128 } | ||
|  | body: | | ||
|  |   bb.0: | ||
|  |     S_NOP 0, implicit-def %0 | ||
|  |     %1 = REG_SEQUENCE %0, %subreg.sub0 | ||
|  |     S_BRANCH %bb.1 | ||
|  | 
 | ||
|  |   bb.1: | ||
|  |     %2 = PHI %1, %bb.0, %3, %bb.1 | ||
|  | 
 | ||
|  |     ; rotate subreg lanes, skipping sub1 | ||
|  |     %3 = REG_SEQUENCE %2.sub3, %subreg.sub0, %2.sub1, %subreg.sub1, %2.sub0, %subreg.sub2, %2.sub2, %subreg.sub3 | ||
|  | 
 | ||
|  |     S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc | ||
|  |     S_BRANCH %bb.2 | ||
|  | 
 | ||
|  |   bb.2: | ||
|  |     S_NOP 0, implicit %2.sub0 | ||
|  |     S_NOP 0, implicit undef %2.sub1 | ||
|  |     S_NOP 0, implicit %2.sub2 | ||
|  |     S_NOP 0, implicit %2.sub3 | ||
|  | ... |