Create subranges for new intervals resulting from live interval splitting

The register allocator can split a live interval of a register into a set
of smaller intervals. After the allocation of registers is complete, the
rewriter will modify the IR to replace virtual registers with the corres-
ponding physical registers. At this stage, if a register corresponding
to a subregister of a virtual register is used, the rewriter will check
if that subregister is undefined, and if so, it will add the <undef> flag
to the machine operand. The function verifying liveness of the subregis-
ter would assume that it is undefined, unless any of the subranges of the
live interval proves otherwise.
The problem is that the live intervals created during splitting do not
have any subranges, even if the original parent interval did. This could
result in the <undef> flag placed on a register that is actually defined.

Differential Revision: http://reviews.llvm.org/D21189

llvm-svn: 279625

2 files changed, 256 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AMDGPU/subreg-intervals.mir b/llvm/test/CodeGen/AMDGPU/subreg-intervals.mir
new file mode 100644
index 00000000000..c4e00215159
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/subreg-intervals.mir
@@ -0,0 +1,51 @@
+# RUN: llc -march=amdgcn -run-pass liveintervals -debug-only=regalloc -o /dev/null %s 2>&1 | FileCheck %s
+# REQUIRES: asserts
+
+# CHECK: INTERVALS
+# CHECK: vreg0
+# CHECK-LABEL: Machine code for function test0:
+
+# CHECK: INTERVALS
+# CHECK: vreg0
+# CHECK-LABEL: Machine code for function test1:
+
+--- |
+  define void @test0() { ret void }
+  define void @test1() { ret void }
+...
+---
+name: test0
+registers:
+  - { id: 0, class: sreg_64 }
+body: |
+  bb.0:
+    S_NOP 0, implicit-def %0
+    S_NOP 0, implicit %0
+
+    S_NOP 0, implicit-def undef %0.sub0
+    S_NOP 0, implicit %0
+...
+---
+name: test1
+registers:
+  - { id: 0, class: sreg_64 }
+body: |
+  bb.0:
+    successors: %bb.1, %bb.2
+    S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc
+    S_BRANCH %bb.2
+
+  bb.1:
+    successors: %bb.3
+    S_NOP 0, implicit-def undef %0.sub0
+    S_BRANCH %bb.3
+
+  bb.2:
+    successors: %bb.3
+    S_NOP 0, implicit-def %0
+    S_BRANCH %bb.3
+
+  bb.3:
+    S_NOP 0
+    S_NOP 0, implicit %0
+...
diff --git a/llvm/test/CodeGen/Hexagon/regalloc-bad-undef.mir b/llvm/test/CodeGen/Hexagon/regalloc-bad-undef.mir
new file mode 100644
index 00000000000..8fed2c66da3
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/regalloc-bad-undef.mir
@@ -0,0 +1,205 @@
+# RUN: llc -march=hexagon -hexagon-subreg-liveness -start-after machine-scheduler -stop-after stack-slot-coloring -o - %s | FileCheck %s
+
+--- |
+  target triple = "hexagon"
+
+  ; Function Attrs: nounwind optsize
+  define void @main() #0 {
+  entry:
+    br label %for.body
+
+  for.body:                                         ; preds = %if.end82, %entry
+    %lsr.iv = phi i32 [ %lsr.iv.next, %if.end82 ], [ 524288, %entry ]
+    %call9 = tail call i32 @lrand48() #0
+    %conv10 = sext i32 %call9 to i64
+    %shr11 = lshr i64 %conv10, 9
+    %or12 = or i64 0, %shr11
+    %call14 = tail call i32 @lrand48() #0
+    %conv15138 = zext i32 %call14 to i64
+    %shr16 = lshr i64 %conv15138, 9
+    %0 = call i64 @llvm.hexagon.S2.extractup(i64 %conv15138, i32 22, i32 9)
+    %1 = shl i64 %0, 42
+    %shl17 = shl i64 %shr16, 42
+    %or22 = or i64 0, %1
+    %or26 = or i64 %or22, 0
+    %shr30 = lshr i64 undef, 25
+    %2 = call i64 @llvm.hexagon.S2.extractup(i64 undef, i32 6, i32 25)
+    %and = and i64 %shr30, 63
+    %sub = shl i64 2, %2
+    %add = add i64 %sub, -1
+    %shl37 = shl i64 %add, 0
+    %call38 = tail call i32 @lrand48() #0
+    %conv39141 = zext i32 %call38 to i64
+    %shr40 = lshr i64 %conv39141, 25
+    %3 = call i64 @llvm.hexagon.S2.extractup(i64 %conv39141, i32 6, i32 25)
+    %and41 = and i64 %shr40, 63
+    %sub43 = shl i64 2, %3
+    %add45 = add i64 %sub43, -1
+    %call46 = tail call i32 @lrand48() #0
+    %shr48 = lshr i64 undef, 25
+    %4 = call i64 @llvm.hexagon.S2.extractup(i64 undef, i32 6, i32 25)
+    %and49 = and i64 %shr48, 63
+    %shl50 = shl i64 %add45, %4
+    %and52 = and i64 %shl37, %or12
+    %and54 = and i64 %shl50, %or26
+    store i64 %and54, i64* undef, align 8
+    %cmp56 = icmp eq i64 %and52, 0
+    br i1 %cmp56, label %for.end, label %if.end82
+
+  if.end82:                                         ; preds = %for.body
+    %lsr.iv.next = add nsw i32 %lsr.iv, -1
+    %exitcond = icmp eq i32 %lsr.iv.next, 0
+    br i1 %exitcond, label %for.end, label %for.body
+
+  for.end:                                          ; preds = %if.end82, %for.body
+    unreachable
+  }
+
+  declare i32 @lrand48() #0
+  declare i64 @llvm.hexagon.S2.extractup(i64, i32, i32) #1
+
+  attributes #0 = { nounwind optsize "target-cpu"="hexagonv55" "target-features"="-hvx,-hvx-double" }
+  attributes #1 = { nounwind readnone }
+
+...
+---
+name:            main
+alignment:       2
+tracksRegLiveness: true
+tracksSubRegLiveness: true
+registers:
+  - { id: 0, class: intregs }
+  - { id: 1, class: intregs }
+  - { id: 2, class: intregs }
+  - { id: 3, class: intregs }
+  - { id: 4, class: doubleregs }
+  - { id: 5, class: intregs }
+  - { id: 6, class: doubleregs }
+  - { id: 7, class: doubleregs }
+  - { id: 8, class: doubleregs }
+  - { id: 9, class: doubleregs }
+  - { id: 10, class: intregs }
+  - { id: 11, class: doubleregs }
+  - { id: 12, class: doubleregs }
+  - { id: 13, class: doubleregs }
+  - { id: 14, class: intregs }
+  - { id: 15, class: doubleregs }
+  - { id: 16, class: doubleregs }
+  - { id: 17, class: intregs }
+  - { id: 18, class: doubleregs }
+  - { id: 19, class: intregs }
+  - { id: 20, class: doubleregs }
+  - { id: 21, class: doubleregs }
+  - { id: 22, class: doubleregs }
+  - { id: 23, class: intregs }
+  - { id: 24, class: doubleregs }
+  - { id: 25, class: predregs }
+  - { id: 26, class: predregs }
+  - { id: 27, class: intregs }
+  - { id: 28, class: intregs }
+  - { id: 29, class: doubleregs }
+  - { id: 30, class: intregs }
+  - { id: 31, class: intregs }
+  - { id: 32, class: doubleregs }
+  - { id: 33, class: intregs }
+  - { id: 34, class: intregs }
+  - { id: 35, class: doubleregs }
+  - { id: 36, class: doubleregs }
+  - { id: 37, class: intregs }
+  - { id: 38, class: intregs }
+  - { id: 39, class: doubleregs }
+  - { id: 40, class: doubleregs }
+  - { id: 41, class: intregs }
+  - { id: 42, class: intregs }
+  - { id: 43, class: doubleregs }
+  - { id: 44, class: intregs }
+  - { id: 45, class: intregs }
+  - { id: 46, class: doubleregs }
+  - { id: 47, class: doubleregs }
+  - { id: 48, class: doubleregs }
+  - { id: 49, class: doubleregs }
+  - { id: 50, class: doubleregs }
+  - { id: 51, class: doubleregs }
+  - { id: 52, class: intregs }
+  - { id: 53, class: intregs }
+  - { id: 54, class: intregs }
+  - { id: 55, class: doubleregs }
+  - { id: 56, class: doubleregs }
+  - { id: 57, class: intregs }
+  - { id: 58, class: intregs }
+  - { id: 59, class: intregs }
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    0
+  adjustsStack:    false
+  hasCalls:        true
+  maxCallFrameSize: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+body:             |
+  bb.0.entry:
+    successors: %bb.1.for.body
+
+    %59 = A2_tfrsi 524288
+    undef %32.subreg_hireg = A2_tfrsi 0
+    %8 = S2_extractup undef %9, 6, 25
+    %47 = A2_tfrpi 2
+    %13 = A2_tfrpi -1
+    %13 = S2_asl_r_p_acc %13, %47, %8.subreg_loreg
+    %51 = A2_tfrpi 0
+
+    ; CHECK: %d2 = S2_extractup undef %d0, 6, 25
+    ; CHECK: %d0 = A2_tfrpi 2
+    ; CHECK: %d13 = A2_tfrpi -1
+    ; CHECK-NOT: undef %r4
+
+  bb.1.for.body:
+    successors: %bb.3.for.end, %bb.2.if.end82
+
+    ADJCALLSTACKDOWN 0, implicit-def dead %r29, implicit-def dead %r30, implicit %r31, implicit %r30, implicit %r29
+    J2_call @lrand48, implicit-def dead %d0, implicit-def dead %d1, implicit-def dead %d2, implicit-def dead %d3, implicit-def dead %d4, implicit-def dead %d5, implicit-def dead %d6, implicit-def dead %d7, implicit-def dead %r28, implicit-def dead %r31, implicit-def dead %p0, implicit-def dead %p1, implicit-def dead %p2, implicit-def dead %p3, implicit-def dead %m0, implicit-def dead %m1, implicit-def dead %lc0, implicit-def dead %lc1, implicit-def dead %sa0, implicit-def dead %sa1, implicit-def dead %usr, implicit-def %usr_ovf, implicit-def dead %cs0, implicit-def dead %cs1, implicit-def dead %w0, implicit-def dead %w1, implicit-def dead %w2, implicit-def dead %w3, implicit-def dead %w4, implicit-def dead %w5, implicit-def dead %w6, implicit-def dead %w7, implicit-def dead %w8, implicit-def dead %w9, implicit-def dead %w10, implicit-def dead %w11, implicit-def dead %w12, implicit-def dead %w13, implicit-def dead %w14, implicit-def dead %w15, implicit-def dead %q0, implicit-def dead %q1, implicit-def dead %q2, implicit-def dead %q3, implicit-def %r0
+    ADJCALLSTACKUP 0, 0, implicit-def dead %r29, implicit-def dead %r30, implicit-def dead %r31, implicit %r29
+    undef %29.subreg_loreg = COPY killed %r0
+    %29.subreg_hireg = S2_asr_i_r %29.subreg_loreg, 31
+    ADJCALLSTACKDOWN 0, implicit-def dead %r29, implicit-def dead %r30, implicit %r31, implicit %r30, implicit %r29
+    J2_call @lrand48, implicit-def dead %d0, implicit-def dead %d1, implicit-def dead %d2, implicit-def dead %d3, implicit-def dead %d4, implicit-def dead %d5, implicit-def dead %d6, implicit-def dead %d7, implicit-def dead %r28, implicit-def dead %r31, implicit-def dead %p0, implicit-def dead %p1, implicit-def dead %p2, implicit-def dead %p3, implicit-def dead %m0, implicit-def dead %m1, implicit-def dead %lc0, implicit-def dead %lc1, implicit-def dead %sa0, implicit-def dead %sa1, implicit-def dead %usr, implicit-def %usr_ovf, implicit-def dead %cs0, implicit-def dead %cs1, implicit-def dead %w0, implicit-def dead %w1, implicit-def dead %w2, implicit-def dead %w3, implicit-def dead %w4, implicit-def dead %w5, implicit-def dead %w6, implicit-def dead %w7, implicit-def dead %w8, implicit-def dead %w9, implicit-def dead %w10, implicit-def dead %w11, implicit-def dead %w12, implicit-def dead %w13, implicit-def dead %w14, implicit-def dead %w15, implicit-def dead %q0, implicit-def dead %q1, implicit-def dead %q2, implicit-def dead %q3, implicit-def %r0
+    ADJCALLSTACKUP 0, 0, implicit-def dead %r29, implicit-def dead %r30, implicit-def dead %r31, implicit %r29
+    %32.subreg_loreg = COPY killed %r0
+    %7 = S2_extractup %32, 22, 9
+    ADJCALLSTACKDOWN 0, implicit-def dead %r29, implicit-def dead %r30, implicit %r31, implicit %r30, implicit %r29
+    J2_call @lrand48, implicit-def dead %d0, implicit-def dead %d1, implicit-def dead %d2, implicit-def dead %d3, implicit-def dead %d4, implicit-def dead %d5, implicit-def dead %d6, implicit-def dead %d7, implicit-def dead %r28, implicit-def dead %r31, implicit-def dead %p0, implicit-def dead %p1, implicit-def dead %p2, implicit-def dead %p3, implicit-def dead %m0, implicit-def dead %m1, implicit-def dead %lc0, implicit-def dead %lc1, implicit-def dead %sa0, implicit-def dead %sa1, implicit-def dead %usr, implicit-def %usr_ovf, implicit-def dead %cs0, implicit-def dead %cs1, implicit-def dead %w0, implicit-def dead %w1, implicit-def dead %w2, implicit-def dead %w3, implicit-def dead %w4, implicit-def dead %w5, implicit-def dead %w6, implicit-def dead %w7, implicit-def dead %w8, implicit-def dead %w9, implicit-def dead %w10, implicit-def dead %w11, implicit-def dead %w12, implicit-def dead %w13, implicit-def dead %w14, implicit-def dead %w15, implicit-def dead %q0, implicit-def dead %q1, implicit-def dead %q2, implicit-def dead %q3, implicit-def %r0
+    ADJCALLSTACKUP 0, 0, implicit-def dead %r29, implicit-def dead %r30, implicit-def dead %r31, implicit %r29
+    undef %43.subreg_loreg = COPY killed %r0
+    %43.subreg_hireg = COPY %32.subreg_hireg
+    %16 = S2_extractup %43, 6, 25
+    %18 = A2_tfrpi -1
+    %18 = S2_asl_r_p_acc %18, %47, %16.subreg_loreg
+    ADJCALLSTACKDOWN 0, implicit-def dead %r29, implicit-def dead %r30, implicit %r31, implicit %r30, implicit %r29
+    J2_call @lrand48, implicit-def dead %d0, implicit-def dead %d1, implicit-def dead %d2, implicit-def dead %d3, implicit-def dead %d4, implicit-def dead %d5, implicit-def dead %d6, implicit-def dead %d7, implicit-def dead %r28, implicit-def dead %r31, implicit-def dead %p0, implicit-def dead %p1, implicit-def dead %p2, implicit-def dead %p3, implicit-def dead %m0, implicit-def dead %m1, implicit-def dead %lc0, implicit-def dead %lc1, implicit-def dead %sa0, implicit-def dead %sa1, implicit-def dead %usr, implicit-def %usr_ovf, implicit-def dead %cs0, implicit-def dead %cs1, implicit-def dead %w0, implicit-def dead %w1, implicit-def dead %w2, implicit-def dead %w3, implicit-def dead %w4, implicit-def dead %w5, implicit-def dead %w6, implicit-def dead %w7, implicit-def dead %w8, implicit-def dead %w9, implicit-def dead %w10, implicit-def dead %w11, implicit-def dead %w12, implicit-def dead %w13, implicit-def dead %w14, implicit-def dead %w15, implicit-def dead %q0, implicit-def dead %q1, implicit-def dead %q2, implicit-def dead %q3
+    ADJCALLSTACKUP 0, 0, implicit-def dead %r29, implicit-def dead %r30, implicit-def dead %r31, implicit %r29
+    %22 = S2_asl_r_p %18, %8.subreg_loreg
+    %21 = COPY %13
+    %21 = S2_lsr_i_p_and %21, %29, 9
+    %22 = S2_asl_i_p_and %22, %7, 42
+    S2_storerd_io undef %23, 0, %22 :: (store 8 into `i64* undef`)
+    %25 = C2_cmpeqp %21, %51
+    J2_jumpt %25, %bb.3.for.end, implicit-def dead %pc
+    J2_jump %bb.2.if.end82, implicit-def dead %pc
+
+  bb.2.if.end82:
+    successors: %bb.3.for.end, %bb.1.for.body
+
+    %59 = A2_addi %59, -1
+    %26 = C2_cmpeqi %59, 0
+    J2_jumpf %26, %bb.1.for.body, implicit-def dead %pc
+    J2_jump %bb.3.for.end, implicit-def dead %pc
+
+  bb.3.for.end:
+
+...