[llvm] [JumpThreading] Thread over BB with only an unconditional branch (PR #86312)

via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 16 01:27:38 PDT 2024


https://github.com/XChy updated https://github.com/llvm/llvm-project/pull/86312

>From 0c392edc43284ffb39e781b30ecea8e9ddeb4491 Mon Sep 17 00:00:00 2001
From: XChy <xxs_chy at outlook.com>
Date: Sat, 23 Mar 2024 00:16:25 +0800
Subject: [PATCH 1/2] [JumpThreading][NFC] Precommit tests for pr76609

---
 .../Transforms/JumpThreading/uncond-no-phi.ll | 123 ++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 llvm/test/Transforms/JumpThreading/uncond-no-phi.ll

diff --git a/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll b/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll
new file mode 100644
index 00000000000000..267bf1e497f1cb
--- /dev/null
+++ b/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll
@@ -0,0 +1,123 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes=jump-threading -S < %s | FileCheck %s
+
+define i1 @if_else(i1 %c, i1 %c1) {
+; CHECK-LABEL: define i1 @if_else(
+; CHECK-SAME: i1 [[C:%.*]], i1 [[C1:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C]], label [[THEN:%.*]], label [[RETURN:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br i1 [[C1]], label [[RETURN]], label [[RETURN1:%.*]]
+; CHECK:       else:
+; CHECK-NEXT:    br label [[RETURN1]]
+; CHECK:       return:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i1 [ true, [[RETURN]] ], [ false, [[THEN]] ]
+; CHECK-NEXT:    ret i1 [[RETVAL_0]]
+;
+entry:
+  br i1 %c, label %then, label %else
+
+then:
+  call void @dummy()
+  br i1 %c1, label %else, label %return
+
+else:
+  br label %return
+
+return:
+  %retval.0 = phi i1 [ true, %else ], [ false, %then ]
+  ret i1 %retval.0
+}
+
+define i8 @switch_uncond(i8 %arg) {
+; CHECK-LABEL: define i8 @switch_uncond(
+; CHECK-SAME: i8 [[ARG:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i8 [[ARG]], label [[DEFAULT:%.*]] [
+; CHECK-NEXT:      i8 0, label [[BB1:%.*]]
+; CHECK-NEXT:      i8 1, label [[BB3:%.*]]
+; CHECK-NEXT:      i8 2, label [[BB2:%.*]]
+; CHECK-NEXT:      i8 3, label [[END:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       default:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb1:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ 0, [[BB2]] ], [ 1, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i8 [[PHI]]
+;
+entry:
+  switch i8 %arg, label %default [
+  i8 0, label %bb
+  i8 1, label %bb1
+  i8 2, label %bb2
+  i8 3, label %end
+  ]
+
+default:
+  unreachable
+
+bb:
+  call void @dummy()
+  br label %bb2
+
+bb1:
+  call void @dummy()
+  br label %bb2
+
+; Predecessors of %bb2 are %bb and %bb1, they are not identical.
+; So we can thread %bb2.
+bb2:
+  br label %end
+
+end:
+  %phi = phi i8 [ 0, %bb2 ], [ 1, %entry ]
+  ret i8 %phi
+}
+
+define i8 @switch_uncond_fail(i8 %arg) {
+; CHECK-LABEL: define i8 @switch_uncond_fail(
+; CHECK-SAME: i8 [[ARG:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i8 [[ARG]], label [[DEFAULT:%.*]] [
+; CHECK-NEXT:      i8 0, label [[BB:%.*]]
+; CHECK-NEXT:      i8 1, label [[BB]]
+; CHECK-NEXT:      i8 2, label [[END:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       default:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       bb:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ 0, [[BB]] ], [ 1, [[ENTRY:%.*]] ], [ 2, [[DEFAULT]] ]
+; CHECK-NEXT:    ret i8 [[PHI]]
+;
+entry:
+  switch i8 %arg, label %default [
+  i8 0, label %bb
+  i8 1, label %bb
+  i8 2, label %end
+  ]
+
+default:
+  br label %end
+
+; Predecessor of %bb is only %entry (though there are two in predecessor list),
+; thus it's unthreadable.
+bb:
+  br label %end
+
+end:
+  %phi = phi i8 [ 0, %bb ], [ 1, %entry ], [ 2, %default ]
+  ret i8 %phi
+}
+
+declare void @dummy()

>From e38427fa47bb77ed48a910ba0357abae0e480c5a Mon Sep 17 00:00:00 2001
From: XChy <xxs_chy at outlook.com>
Date: Fri, 22 Mar 2024 23:58:58 +0800
Subject: [PATCH 2/2] [JumpThreading] Thread over basicblocks with only an
 unconditional branch

---
 llvm/lib/Transforms/Utils/Local.cpp           |  10 +-
 llvm/test/CodeGen/AArch64/and-sink.ll         |   9 +-
 .../AArch64/combine-comparisons-by-cse.ll     | 122 +++++++-----------
 llvm/test/CodeGen/Hexagon/vect/zext-v4i1.ll   |  18 +--
 llvm/test/Transforms/JumpThreading/pr79175.ll |   8 +-
 llvm/test/Transforms/JumpThreading/select.ll  |  50 +++----
 .../Transforms/JumpThreading/thread-prob-7.ll |   8 +-
 .../Transforms/JumpThreading/uncond-no-phi.ll |  12 +-
 .../PhaseOrdering/thread-uncond-bb.ll         |  62 +++++++++
 9 files changed, 167 insertions(+), 132 deletions(-)
 create mode 100644 llvm/test/Transforms/PhaseOrdering/thread-uncond-bb.ll

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 380bac9c618077..eb88a3922114bb 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1019,12 +1019,14 @@ CanRedirectPredsOfEmptyBBToSucc(BasicBlock *BB, BasicBlock *Succ,
                                 const SmallPtrSetImpl<BasicBlock *> &SuccPreds,
                                 BasicBlock *&CommonPred) {
 
-  // There must be phis in BB, otherwise BB will be merged into Succ directly
-  if (BB->phis().empty() || Succ->phis().empty())
+  // When Succ has no phis, BB may be merged into Succ directly. We don't need
+  // to redirect the predecessors of BB in this case.
+  if (Succ->phis().empty())
     return false;
 
-  // BB must have predecessors not shared that can be redirected to Succ
-  if (!BB->hasNPredecessorsOrMore(2))
+  // BB must have multiple different predecessors, so that at least one of
+  // predecessors can be redirected to Succ, except the common predecessor.
+  if (BB->getUniquePredecessor() || pred_empty(BB))
     return false;
 
   // Get single common predecessors of both BB and Succ
diff --git a/llvm/test/CodeGen/AArch64/and-sink.ll b/llvm/test/CodeGen/AArch64/and-sink.ll
index f298a55dab721e..a57e9d54f3078e 100644
--- a/llvm/test/CodeGen/AArch64/and-sink.ll
+++ b/llvm/test/CodeGen/AArch64/and-sink.ll
@@ -11,15 +11,14 @@
 define dso_local i32 @and_sink1(i32 %a, i1 %c) {
 ; CHECK-LABEL: and_sink1:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    tbz w1, #0, .LBB0_3
+; CHECK-NEXT:    tbz w1, #0, .LBB0_2
 ; CHECK-NEXT:  // %bb.1: // %bb0
+; CHECK-NEXT:    tst w0, #0x4
 ; CHECK-NEXT:    adrp x8, A
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    str wzr, [x8, :lo12:A]
-; CHECK-NEXT:    tbnz w0, #2, .LBB0_3
-; CHECK-NEXT:  // %bb.2:
-; CHECK-NEXT:    mov w0, #1 // =0x1
 ; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB0_3: // %bb2
+; CHECK-NEXT:  .LBB0_2:
 ; CHECK-NEXT:    mov w0, wzr
 ; CHECK-NEXT:    ret
 
diff --git a/llvm/test/CodeGen/AArch64/combine-comparisons-by-cse.ll b/llvm/test/CodeGen/AArch64/combine-comparisons-by-cse.ll
index 6449c3e11d6672..dde3e81833a63d 100644
--- a/llvm/test/CodeGen/AArch64/combine-comparisons-by-cse.ll
+++ b/llvm/test/CodeGen/AArch64/combine-comparisons-by-cse.ll
@@ -13,10 +13,10 @@ define i32 @combine_gt_ge_10() #0 {
 ; CHECK:       // %bb.0: // %entry
 ; CHECK-NEXT:    adrp x8, :got:a
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:a]
-; CHECK-NEXT:    ldr w8, [x8]
-; CHECK-NEXT:    cmp w8, #10
+; CHECK-NEXT:    ldr w9, [x8]
 ; CHECK-NEXT:    adrp x8, :got:b
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:b]
+; CHECK-NEXT:    cmp w9, #10
 ; CHECK-NEXT:    b.le .LBB0_3
 ; CHECK-NEXT:  // %bb.1: // %land.lhs.true
 ; CHECK-NEXT:    adrp x9, :got:c
@@ -29,18 +29,17 @@ define i32 @combine_gt_ge_10() #0 {
 ; CHECK-NEXT:    mov w0, #1 // =0x1
 ; CHECK-NEXT:    ret
 ; CHECK-NEXT:  .LBB0_3: // %lor.lhs.false
-; CHECK-NEXT:    b.lt .LBB0_6
+; CHECK-NEXT:    cmp w9, #10
+; CHECK-NEXT:    b.lt .LBB0_5
 ; CHECK-NEXT:  .LBB0_4: // %land.lhs.true3
 ; CHECK-NEXT:    adrp x9, :got:d
 ; CHECK-NEXT:    ldr x9, [x9, :got_lo12:d]
 ; CHECK-NEXT:    ldr w8, [x8]
 ; CHECK-NEXT:    ldr w9, [x9]
 ; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    b.ne .LBB0_6
-; CHECK-NEXT:  // %bb.5:
-; CHECK-NEXT:    mov w0, #1 // =0x1
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB0_6: // %if.end
+; CHECK-NEXT:  .LBB0_5:
 ; CHECK-NEXT:    mov w0, wzr
 ; CHECK-NEXT:    ret
 entry:
@@ -145,10 +144,10 @@ define i32 @combine_lt_ge_5() #0 {
 ; CHECK:       // %bb.0: // %entry
 ; CHECK-NEXT:    adrp x8, :got:a
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:a]
-; CHECK-NEXT:    ldr w8, [x8]
-; CHECK-NEXT:    cmp w8, #5
+; CHECK-NEXT:    ldr w9, [x8]
 ; CHECK-NEXT:    adrp x8, :got:b
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:b]
+; CHECK-NEXT:    cmp w9, #5
 ; CHECK-NEXT:    b.ge .LBB2_3
 ; CHECK-NEXT:  // %bb.1: // %land.lhs.true
 ; CHECK-NEXT:    adrp x9, :got:c
@@ -161,18 +160,17 @@ define i32 @combine_lt_ge_5() #0 {
 ; CHECK-NEXT:    mov w0, #1 // =0x1
 ; CHECK-NEXT:    ret
 ; CHECK-NEXT:  .LBB2_3: // %lor.lhs.false
-; CHECK-NEXT:    b.gt .LBB2_6
+; CHECK-NEXT:    cmp w9, #5
+; CHECK-NEXT:    b.gt .LBB2_5
 ; CHECK-NEXT:  .LBB2_4: // %land.lhs.true3
 ; CHECK-NEXT:    adrp x9, :got:d
 ; CHECK-NEXT:    ldr x9, [x9, :got_lo12:d]
 ; CHECK-NEXT:    ldr w8, [x8]
 ; CHECK-NEXT:    ldr w9, [x9]
 ; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    b.ne .LBB2_6
-; CHECK-NEXT:  // %bb.5:
-; CHECK-NEXT:    mov w0, #1 // =0x1
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB2_6: // %if.end
+; CHECK-NEXT:  .LBB2_5:
 ; CHECK-NEXT:    mov w0, wzr
 ; CHECK-NEXT:    ret
 entry:
@@ -499,24 +497,17 @@ define i32 @do_nothing_if_resultant_opcodes_would_differ() #0 {
 ; CHECK-NEXT:  // %bb.3: // %while.cond.while.end_crit_edge
 ; CHECK-NEXT:    ldr w8, [x19]
 ; CHECK-NEXT:  .LBB7_4: // %while.end
-; CHECK-NEXT:    cmp w8, #1
-; CHECK-NEXT:    b.gt .LBB7_7
-; CHECK-NEXT:  // %bb.5: // %land.lhs.true
-; CHECK-NEXT:    adrp x8, :got:b
-; CHECK-NEXT:    adrp x9, :got:d
-; CHECK-NEXT:    ldr x8, [x8, :got_lo12:b]
-; CHECK-NEXT:    ldr x9, [x9, :got_lo12:d]
-; CHECK-NEXT:    ldr w8, [x8]
-; CHECK-NEXT:    ldr w9, [x9]
-; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    b.ne .LBB7_7
-; CHECK-NEXT:  // %bb.6:
-; CHECK-NEXT:    mov w0, #123 // =0x7b
-; CHECK-NEXT:    b .LBB7_8
-; CHECK-NEXT:  .LBB7_7: // %if.end
-; CHECK-NEXT:    mov w0, wzr
-; CHECK-NEXT:  .LBB7_8: // %return
+; CHECK-NEXT:    adrp x9, :got:b
+; CHECK-NEXT:    adrp x10, :got:d
+; CHECK-NEXT:    ldr x9, [x9, :got_lo12:b]
+; CHECK-NEXT:    ldr x10, [x10, :got_lo12:d]
 ; CHECK-NEXT:    ldp x20, x19, [sp, #16] // 16-byte Folded Reload
+; CHECK-NEXT:    ldr w9, [x9]
+; CHECK-NEXT:    ldr w10, [x10]
+; CHECK-NEXT:    cmp w9, w10
+; CHECK-NEXT:    ccmp w8, #2, #0, eq
+; CHECK-NEXT:    mov w8, #123 // =0x7b
+; CHECK-NEXT:    csel w0, w8, wzr, lt
 ; CHECK-NEXT:    ldr x30, [sp], #32 // 8-byte Folded Reload
 ; CHECK-NEXT:    .cfi_def_cfa_offset 0
 ; CHECK-NEXT:    .cfi_restore w19
@@ -564,52 +555,42 @@ return:                                           ; preds = %if.end, %land.lhs.t
 define i32 @do_nothing_if_compares_can_not_be_adjusted_to_each_other() #0 {
 ; CHECK-LABEL: do_nothing_if_compares_can_not_be_adjusted_to_each_other:
 ; CHECK:       // %bb.0: // %entry
-; CHECK-NEXT:    stp x30, x19, [sp, #-16]! // 16-byte Folded Spill
-; CHECK-NEXT:    .cfi_def_cfa_offset 16
-; CHECK-NEXT:    .cfi_offset w19, -8
-; CHECK-NEXT:    .cfi_offset w30, -16
-; CHECK-NEXT:    .cfi_remember_state
 ; CHECK-NEXT:    adrp x8, :got:a
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:a]
 ; CHECK-NEXT:    ldr w8, [x8]
 ; CHECK-NEXT:    cmp w8, #0
-; CHECK-NEXT:    b.gt .LBB8_3
+; CHECK-NEXT:    b.gt .LBB8_4
 ; CHECK-NEXT:  // %bb.1: // %while.body.preheader
+; CHECK-NEXT:    stp x30, x19, [sp, #-16]! // 16-byte Folded Spill
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    .cfi_offset w19, -8
+; CHECK-NEXT:    .cfi_offset w30, -16
 ; CHECK-NEXT:    sub w19, w8, #1
 ; CHECK-NEXT:  .LBB8_2: // %while.body
 ; CHECK-NEXT:    // =>This Inner Loop Header: Depth=1
 ; CHECK-NEXT:    bl do_something
 ; CHECK-NEXT:    adds w19, w19, #1
 ; CHECK-NEXT:    b.mi .LBB8_2
-; CHECK-NEXT:  .LBB8_3: // %while.end
-; CHECK-NEXT:    adrp x8, :got:c
-; CHECK-NEXT:    ldr x8, [x8, :got_lo12:c]
-; CHECK-NEXT:    ldr w8, [x8]
-; CHECK-NEXT:    cmn w8, #2
-; CHECK-NEXT:    b.lt .LBB8_6
-; CHECK-NEXT:  // %bb.4: // %land.lhs.true
+; CHECK-NEXT:  // %bb.3:
+; CHECK-NEXT:    ldp x30, x19, [sp], #16 // 16-byte Folded Reload
+; CHECK-NEXT:    .cfi_def_cfa_offset 0
+; CHECK-NEXT:    .cfi_restore w19
+; CHECK-NEXT:    .cfi_restore w30
+; CHECK-NEXT:  .LBB8_4: // %while.end
 ; CHECK-NEXT:    adrp x8, :got:b
 ; CHECK-NEXT:    adrp x9, :got:d
+; CHECK-NEXT:    adrp x10, :got:c
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:b]
 ; CHECK-NEXT:    ldr x9, [x9, :got_lo12:d]
+; CHECK-NEXT:    ldr x10, [x10, :got_lo12:c]
 ; CHECK-NEXT:    ldr w8, [x8]
 ; CHECK-NEXT:    ldr w9, [x9]
+; CHECK-NEXT:    ldr w10, [x10]
 ; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    b.ne .LBB8_6
-; CHECK-NEXT:  // %bb.5:
-; CHECK-NEXT:    mov w0, #123 // =0x7b
-; CHECK-NEXT:    ldp x30, x19, [sp], #16 // 16-byte Folded Reload
-; CHECK-NEXT:    .cfi_def_cfa_offset 0
-; CHECK-NEXT:    .cfi_restore w19
-; CHECK-NEXT:    .cfi_restore w30
-; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB8_6: // %if.end
-; CHECK-NEXT:    .cfi_restore_state
-; CHECK-NEXT:    mov w0, wzr
-; CHECK-NEXT:    ldp x30, x19, [sp], #16 // 16-byte Folded Reload
-; CHECK-NEXT:    .cfi_def_cfa_offset 0
-; CHECK-NEXT:    .cfi_restore w19
-; CHECK-NEXT:    .cfi_restore w30
+; CHECK-NEXT:    mov w8, #-3 // =0xfffffffd
+; CHECK-NEXT:    ccmp w10, w8, #4, eq
+; CHECK-NEXT:    mov w8, #123 // =0x7b
+; CHECK-NEXT:    csel w0, w8, wzr, gt
 ; CHECK-NEXT:    ret
 entry:
   %0 = load i32, ptr @a, align 4
@@ -782,12 +763,14 @@ define i32 @combine_gt_ge_sel(i64 %v, ptr %p) #0 {
 ; CHECK-NEXT:    cmp w8, #0
 ; CHECK-NEXT:    csel x9, x0, xzr, gt
 ; CHECK-NEXT:    str x9, [x1]
-; CHECK-NEXT:    b.le .LBB11_2
+; CHECK-NEXT:    b.le .LBB11_3
 ; CHECK-NEXT:  // %bb.1: // %lor.lhs.false
 ; CHECK-NEXT:    cmp w8, #2
-; CHECK-NEXT:    b.ge .LBB11_4
-; CHECK-NEXT:    b .LBB11_6
-; CHECK-NEXT:  .LBB11_2: // %land.lhs.true
+; CHECK-NEXT:    b.ge .LBB11_5
+; CHECK-NEXT:  // %bb.2:
+; CHECK-NEXT:    mov w0, wzr
+; CHECK-NEXT:    ret
+; CHECK-NEXT:  .LBB11_3: // %land.lhs.true
 ; CHECK-NEXT:    adrp x8, :got:b
 ; CHECK-NEXT:    adrp x9, :got:c
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:b]
@@ -795,11 +778,11 @@ define i32 @combine_gt_ge_sel(i64 %v, ptr %p) #0 {
 ; CHECK-NEXT:    ldr w8, [x8]
 ; CHECK-NEXT:    ldr w9, [x9]
 ; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    b.ne .LBB11_4
-; CHECK-NEXT:  // %bb.3:
+; CHECK-NEXT:    b.ne .LBB11_5
+; CHECK-NEXT:  // %bb.4:
 ; CHECK-NEXT:    mov w0, #1 // =0x1
 ; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB11_4: // %land.lhs.true3
+; CHECK-NEXT:  .LBB11_5: // %land.lhs.true3
 ; CHECK-NEXT:    adrp x8, :got:b
 ; CHECK-NEXT:    adrp x9, :got:d
 ; CHECK-NEXT:    ldr x8, [x8, :got_lo12:b]
@@ -807,12 +790,7 @@ define i32 @combine_gt_ge_sel(i64 %v, ptr %p) #0 {
 ; CHECK-NEXT:    ldr w8, [x8]
 ; CHECK-NEXT:    ldr w9, [x9]
 ; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    b.ne .LBB11_6
-; CHECK-NEXT:  // %bb.5:
-; CHECK-NEXT:    mov w0, #1 // =0x1
-; CHECK-NEXT:    ret
-; CHECK-NEXT:  .LBB11_6: // %if.end
-; CHECK-NEXT:    mov w0, wzr
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
 entry:
   %0 = load i32, ptr @a, align 4
diff --git a/llvm/test/CodeGen/Hexagon/vect/zext-v4i1.ll b/llvm/test/CodeGen/Hexagon/vect/zext-v4i1.ll
index dddc4bd953d7ac..c33c81841be65e 100644
--- a/llvm/test/CodeGen/Hexagon/vect/zext-v4i1.ll
+++ b/llvm/test/CodeGen/Hexagon/vect/zext-v4i1.ll
@@ -10,12 +10,13 @@ define i32 @fred(ptr %a0) #0 {
 ; CHECK-LABEL: fred:
 ; CHECK:       // %bb.0: // %b0
 ; CHECK-NEXT:    {
-; CHECK-NEXT:     if (p0) jump:nt .LBB0_2
+; CHECK-NEXT:     r1:0 = combine(r0,#0)
+; CHECK-NEXT:     if (p0) jumpr r31
 ; CHECK-NEXT:    }
-; CHECK-NEXT:  // %bb.1: // %b2
+; CHECK-NEXT:  .LBB0_1: // %b2
 ; CHECK-NEXT:    {
 ; CHECK-NEXT:     r3:2 = combine(#0,#0)
-; CHECK-NEXT:     r1:0 = memd(r0+#0)
+; CHECK-NEXT:     r1:0 = memd(r1+#0)
 ; CHECK-NEXT:    }
 ; CHECK-NEXT:    {
 ; CHECK-NEXT:     p0 = vcmph.eq(r1:0,r3:2)
@@ -27,16 +28,7 @@ define i32 @fred(ptr %a0) #0 {
 ; CHECK-NEXT:     r0 = and(r0,#1)
 ; CHECK-NEXT:    }
 ; CHECK-NEXT:    {
-; CHECK-NEXT:     p0 = cmp.eq(r0,#11)
-; CHECK-NEXT:     r0 = #1
-; CHECK-NEXT:    }
-; CHECK-NEXT:    {
-; CHECK-NEXT:     if (p0) r0 = #0
-; CHECK-NEXT:     jumpr r31
-; CHECK-NEXT:    }
-; CHECK-NEXT:  .LBB0_2: // %b14
-; CHECK-NEXT:    {
-; CHECK-NEXT:     r0 = #0
+; CHECK-NEXT:     r0 = !cmp.eq(r0,#11)
 ; CHECK-NEXT:     jumpr r31
 ; CHECK-NEXT:    }
 b0:
diff --git a/llvm/test/Transforms/JumpThreading/pr79175.ll b/llvm/test/Transforms/JumpThreading/pr79175.ll
index 2c7ee0770cdc73..cce30ce079999c 100644
--- a/llvm/test/Transforms/JumpThreading/pr79175.ll
+++ b/llvm/test/Transforms/JumpThreading/pr79175.ll
@@ -17,11 +17,11 @@ define i32 @test(i64 %idx, i32 %val) {
 ; CHECK:       cond.end:
 ; CHECK-NEXT:    [[CMP_I:%.*]] = icmp sgt i32 [[VAL]], 0
 ; CHECK-NEXT:    [[COND_FR:%.*]] = freeze i1 [[CMP_I]]
-; CHECK-NEXT:    br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP0:%.*]]
-; CHECK:       cond.end.thread:
-; CHECK-NEXT:    br label [[TMP0]]
+; CHECK-NEXT:    br i1 [[COND_FR]], label [[TMP0:%.*]], label [[COND_END_THREAD]]
 ; CHECK:       0:
-; CHECK-NEXT:    [[TMP1:%.*]] = phi i32 [ 0, [[COND_END_THREAD]] ], [ [[VAL]], [[COND_END]] ]
+; CHECK-NEXT:    br label [[COND_END_THREAD]]
+; CHECK:       cond.end.thread:
+; CHECK-NEXT:    [[TMP1:%.*]] = phi i32 [ [[VAL]], [[COND_END]] ], [ 0, [[TMP0]] ], [ 0, [[FOR_BODY]] ]
 ; CHECK-NEXT:    [[F_IDX:%.*]] = getelementptr inbounds i32, ptr @f, i64 [[IDX]]
 ; CHECK-NEXT:    store i32 [[TMP1]], ptr [[F_IDX]], align 4
 ; CHECK-NEXT:    [[F_RELOAD:%.*]] = load i32, ptr @f, align 4
diff --git a/llvm/test/Transforms/JumpThreading/select.ll b/llvm/test/Transforms/JumpThreading/select.ll
index 4ec55a66bb8ac1..27ebf4c25da509 100644
--- a/llvm/test/Transforms/JumpThreading/select.ll
+++ b/llvm/test/Transforms/JumpThreading/select.ll
@@ -1,6 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
 ; RUN: opt -S -passes="jump-threading" -debug-only=branch-prob < %s 2>&1 | FileCheck %s
-; RUN: opt -S -passes="require<branch-prob>,jump-threading" -debug-only=branch-prob < %s 2>&1 | FileCheck -check-prefixes=CHECK,CHECK-BPI %s
+; RUN: opt -S -passes="require<branch-prob>,jump-threading" -debug-only=branch-prob  -disable-output < %s 2>&1 | FileCheck -check-prefix=CHECK-BPI %s
 ; REQUIRES: asserts
 
 ; CHECK-BPI-LABEL:  ---- Branch Probability Info : unfold1 ----
@@ -21,7 +21,7 @@ declare void @quux()
 ; booleans where at least one operand is true/false/undef.
 
 ;.
-; CHECK: @[[ANCHOR:[a-zA-Z0-9_$"\\.-]+]] = constant [3 x ptr] [ptr blockaddress(@test_indirectbr, [[L1:%.*]]), ptr inttoptr (i32 1 to ptr), ptr blockaddress(@test_indirectbr, [[L3:%.*]])]
+; CHECK: @anchor = constant [3 x ptr] [ptr blockaddress(@test_indirectbr, %L1), ptr inttoptr (i32 1 to ptr), ptr blockaddress(@test_indirectbr, %L3)]
 ;.
 define void @test_br(i1 %cond, i1 %value) nounwind {
 ; CHECK-LABEL: @test_br(
@@ -66,8 +66,8 @@ define void @test_switch(i1 %cond, i8 %value) nounwind {
 ; CHECK-NEXT:    call void @quux()
 ; CHECK-NEXT:    [[EXPR:%.*]] = select i1 [[COND]], i8 1, i8 [[VALUE:%.*]]
 ; CHECK-NEXT:    switch i8 [[EXPR]], label [[L3:%.*]] [
-; CHECK-NEXT:    i8 1, label [[L1]]
-; CHECK-NEXT:    i8 2, label [[L2:%.*]]
+; CHECK-NEXT:      i8 1, label [[L1]]
+; CHECK-NEXT:      i8 2, label [[L2:%.*]]
 ; CHECK-NEXT:    ]
 ; CHECK:       L1:
 ; CHECK-NEXT:    call void @foo()
@@ -192,8 +192,8 @@ define void @test_switch_cmp(i1 %cond, i32 %val, i8 %value) nounwind {
 ; CHECK:       0:
 ; CHECK-NEXT:    [[TMP1:%.*]] = phi i8 [ [[VALUE:%.*]], [[L0]] ]
 ; CHECK-NEXT:    switch i8 [[TMP1]], label [[L3:%.*]] [
-; CHECK-NEXT:    i8 1, label [[L1]]
-; CHECK-NEXT:    i8 2, label [[L2:%.*]]
+; CHECK-NEXT:      i8 1, label [[L1]]
+; CHECK-NEXT:      i8 2, label [[L2:%.*]]
 ; CHECK-NEXT:    ]
 ; CHECK:       L1:
 ; CHECK-NEXT:    call void @foo()
@@ -237,8 +237,8 @@ define void @test_switch_default(ptr nocapture %status) nounwind {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr [[STATUS:%.*]], align 4
 ; CHECK-NEXT:    switch i32 [[TMP0]], label [[L2:%.*]] [
-; CHECK-NEXT:    i32 5061, label [[L2_THREAD:%.*]]
-; CHECK-NEXT:    i32 0, label [[L2]]
+; CHECK-NEXT:      i32 5061, label [[L2_THREAD:%.*]]
+; CHECK-NEXT:      i32 0, label [[L2]]
 ; CHECK-NEXT:    ]
 ; CHECK:       L2.thread:
 ; CHECK-NEXT:    store i32 10025, ptr [[STATUS]], align 4
@@ -377,21 +377,21 @@ define i32 @unfold3(i32 %u, i32 %v, i32 %w, i32 %x, i32 %y, i32 %z, i32 %j) noun
 ; CHECK-NEXT:    br i1 [[CMP_I]], label [[DOTEXIT_THREAD4:%.*]], label [[COND_FALSE_I:%.*]]
 ; CHECK:       cond.false.i:
 ; CHECK-NEXT:    [[CMP4_I:%.*]] = icmp sgt i32 [[U]], [[V]]
-; CHECK-NEXT:    br i1 [[CMP4_I]], label [[DOTEXIT_THREAD:%.*]], label [[COND_FALSE_6_I:%.*]]
+; CHECK-NEXT:    br i1 [[CMP4_I]], label [[DOTEXIT_THREAD4]], label [[COND_FALSE_6_I:%.*]]
 ; CHECK:       cond.false.6.i:
 ; CHECK-NEXT:    [[CMP8_I:%.*]] = icmp slt i32 [[W:%.*]], [[X:%.*]]
 ; CHECK-NEXT:    br i1 [[CMP8_I]], label [[DOTEXIT_THREAD4]], label [[COND_FALSE_10_I:%.*]]
 ; CHECK:       cond.false.10.i:
 ; CHECK-NEXT:    [[CMP13_I:%.*]] = icmp sgt i32 [[W]], [[X]]
-; CHECK-NEXT:    br i1 [[CMP13_I]], label [[DOTEXIT_THREAD]], label [[DOTEXIT:%.*]]
+; CHECK-NEXT:    br i1 [[CMP13_I]], label [[DOTEXIT_THREAD4]], label [[DOTEXIT:%.*]]
 ; CHECK:       .exit:
 ; CHECK-NEXT:    [[PHITMP:%.*]] = icmp sge i32 [[Y:%.*]], [[Z:%.*]]
 ; CHECK-NEXT:    [[COND_FR:%.*]] = freeze i1 [[PHITMP]]
-; CHECK-NEXT:    br i1 [[COND_FR]], label [[DOTEXIT_THREAD]], label [[DOTEXIT_THREAD4]]
-; CHECK:       .exit.thread:
+; CHECK-NEXT:    br i1 [[COND_FR]], label [[DOTEXIT_THREAD:%.*]], label [[DOTEXIT_THREAD4]]
+; CHECK:       0:
 ; CHECK-NEXT:    br label [[DOTEXIT_THREAD4]]
-; CHECK:       .exit.thread4:
-; CHECK-NEXT:    [[TMP0:%.*]] = phi i32 [ [[J]], [[DOTEXIT_THREAD]] ], [ [[ADD3]], [[DOTEXIT]] ], [ [[ADD3]], [[ENTRY:%.*]] ], [ [[ADD3]], [[COND_FALSE_6_I]] ]
+; CHECK:       .exit.thread:
+; CHECK-NEXT:    [[TMP0:%.*]] = phi i32 [ [[ADD3]], [[DOTEXIT]] ], [ [[J]], [[DOTEXIT_THREAD]] ], [ [[J]], [[COND_FALSE_I]] ], [ [[J]], [[COND_FALSE_10_I]] ], [ [[ADD3]], [[ENTRY:%.*]] ], [ [[ADD3]], [[COND_FALSE_6_I]] ]
 ; CHECK-NEXT:    ret i32 [[TMP0]]
 ;
 entry:
@@ -430,23 +430,23 @@ define i32 @unfold4(i32 %u, i32 %v, i32 %w, i32 %x, i32 %y, i32 %z, i32 %j) noun
 ; CHECK-NEXT:    br i1 [[CMP_I]], label [[DOTEXIT_THREAD:%.*]], label [[COND_FALSE_I:%.*]]
 ; CHECK:       cond.false.i:
 ; CHECK-NEXT:    [[CMP4_I:%.*]] = icmp sgt i32 [[U]], [[V]]
-; CHECK-NEXT:    br i1 [[CMP4_I]], label [[DOTEXIT_THREAD5:%.*]], label [[COND_FALSE_6_I:%.*]]
+; CHECK-NEXT:    br i1 [[CMP4_I]], label [[DOTEXIT_THREAD]], label [[COND_FALSE_6_I:%.*]]
 ; CHECK:       cond.false.6.i:
 ; CHECK-NEXT:    [[CMP8_I:%.*]] = icmp slt i32 [[W:%.*]], [[X:%.*]]
 ; CHECK-NEXT:    br i1 [[CMP8_I]], label [[DOTEXIT_THREAD]], label [[COND_FALSE_10_I:%.*]]
 ; CHECK:       cond.false.10.i:
 ; CHECK-NEXT:    [[CMP13_I:%.*]] = icmp sgt i32 [[W]], [[X]]
-; CHECK-NEXT:    br i1 [[CMP13_I]], label [[DOTEXIT_THREAD5]], label [[DOTEXIT:%.*]]
+; CHECK-NEXT:    br i1 [[CMP13_I]], label [[DOTEXIT_THREAD]], label [[DOTEXIT:%.*]]
 ; CHECK:       .exit:
 ; CHECK-NEXT:    [[CMP19_I:%.*]] = icmp sge i32 [[Y:%.*]], [[Z:%.*]]
 ; CHECK-NEXT:    [[CONV:%.*]] = zext i1 [[CMP19_I]] to i32
 ; CHECK-NEXT:    [[LNOT_I18:%.*]] = icmp eq i32 [[CONV]], 1
 ; CHECK-NEXT:    [[COND_FR:%.*]] = freeze i1 [[LNOT_I18]]
-; CHECK-NEXT:    br i1 [[COND_FR]], label [[DOTEXIT_THREAD]], label [[DOTEXIT_THREAD5]]
+; CHECK-NEXT:    br i1 [[COND_FR]], label [[TMP1:%.*]], label [[DOTEXIT_THREAD]]
+; CHECK:       0:
+; CHECK-NEXT:    br label [[DOTEXIT_THREAD]]
 ; CHECK:       .exit.thread:
-; CHECK-NEXT:    br label [[DOTEXIT_THREAD5]]
-; CHECK:       .exit.thread5:
-; CHECK-NEXT:    [[TMP0:%.*]] = phi i32 [ [[J]], [[DOTEXIT_THREAD]] ], [ [[ADD3]], [[DOTEXIT]] ], [ [[ADD3]], [[COND_FALSE_I]] ], [ [[ADD3]], [[COND_FALSE_10_I]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = phi i32 [ [[ADD3]], [[DOTEXIT]] ], [ [[J]], [[TMP1]] ], [ [[J]], [[ENTRY:%.*]] ], [ [[J]], [[COND_FALSE_6_I]] ], [ [[ADD3]], [[COND_FALSE_I]] ], [ [[ADD3]], [[COND_FALSE_10_I]] ]
 ; CHECK-NEXT:    ret i32 [[TMP0]]
 ;
 entry:
@@ -560,10 +560,10 @@ define void @test_func(ptr nocapture readonly %a, ptr nocapture readonly %b, ptr
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[LOCAL_VAR_0:%.*]] = phi i32 [ [[TMP1]], [[FOR_BODY]] ]
 ; CHECK-NEXT:    switch i32 [[LOCAL_VAR_0]], label [[SW_DEFAULT]] [
-; CHECK-NEXT:    i32 2, label [[SW_BB]]
-; CHECK-NEXT:    i32 4, label [[SW_BB7]]
-; CHECK-NEXT:    i32 5, label [[SW_BB8:%.*]]
-; CHECK-NEXT:    i32 7, label [[SW_BB9:%.*]]
+; CHECK-NEXT:      i32 2, label [[SW_BB]]
+; CHECK-NEXT:      i32 4, label [[SW_BB7]]
+; CHECK-NEXT:      i32 5, label [[SW_BB8:%.*]]
+; CHECK-NEXT:      i32 7, label [[SW_BB9:%.*]]
 ; CHECK-NEXT:    ]
 ; CHECK:       sw.bb:
 ; CHECK-NEXT:    call void @foo()
@@ -674,3 +674,5 @@ if.end:
 ; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i64 1984}
 ; CHECK: [[PROF1]] = !{!"branch_weights", i64 1073741824, i64 3221225472}
 ;.
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; CHECK-BPI: {{.*}}
diff --git a/llvm/test/Transforms/JumpThreading/thread-prob-7.ll b/llvm/test/Transforms/JumpThreading/thread-prob-7.ll
index 8c9d89871d00b3..4623a579be48f6 100644
--- a/llvm/test/Transforms/JumpThreading/thread-prob-7.ll
+++ b/llvm/test/Transforms/JumpThreading/thread-prob-7.ll
@@ -14,15 +14,15 @@ define i32 @func0(i32 %a0, i32 %a1) !prof !0 {
 ; CHECK-NEXT:    br i1 [[CMP1]], label [[BB_JOIN_THREAD:%.*]], label [[TEST2_FALSE:%.*]], !prof [[PROF2:![0-9]+]]
 ; CHECK:       test2_false:
 ; CHECK-NEXT:    call void @foobar()
-; CHECK-NEXT:    br label [[TMP0:%.*]]
+; CHECK-NEXT:    br label [[BB_JOIN_THREAD]]
 ; CHECK:       bb_join:
 ; CHECK-NEXT:    [[C:%.*]] = phi i1 [ [[CX]], [[ENTRY:%.*]] ]
 ; CHECK-NEXT:    [[COND_FR:%.*]] = freeze i1 [[C]]
-; CHECK-NEXT:    br i1 [[COND_FR]], label [[BB_JOIN_THREAD]], label [[TMP0]], !prof [[PROF3:![0-9]+]]
+; CHECK-NEXT:    br i1 [[COND_FR]], label [[BB_JOIN_THREAD1:%.*]], label [[BB_JOIN_THREAD]], !prof [[PROF3:![0-9]+]]
 ; CHECK:       bb_join.thread:
-; CHECK-NEXT:    br label [[TMP0]]
+; CHECK-NEXT:    br label [[BB_JOIN_THREAD]]
 ; CHECK:       0:
-; CHECK-NEXT:    [[TMP1:%.*]] = phi i32 [ 42, [[BB_JOIN_THREAD]] ], [ 7, [[BB_JOIN]] ], [ 7, [[TEST2_FALSE]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = phi i32 [ 7, [[BB_JOIN]] ], [ 7, [[TEST2_FALSE]] ], [ 42, [[TEST2]] ], [ 42, [[BB_JOIN_THREAD1]] ]
 ; CHECK-NEXT:    ret i32 [[TMP1]]
 ;
 entry:
diff --git a/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll b/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll
index 267bf1e497f1cb..6104e8f8778bc0 100644
--- a/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll
+++ b/llvm/test/Transforms/JumpThreading/uncond-no-phi.ll
@@ -8,11 +8,11 @@ define i1 @if_else(i1 %c, i1 %c1) {
 ; CHECK-NEXT:    br i1 [[C]], label [[THEN:%.*]], label [[RETURN:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br i1 [[C1]], label [[RETURN]], label [[RETURN1:%.*]]
+; CHECK-NEXT:    br i1 [[C1]], label [[ELSE:%.*]], label [[RETURN]]
 ; CHECK:       else:
-; CHECK-NEXT:    br label [[RETURN1]]
+; CHECK-NEXT:    br label [[RETURN]]
 ; CHECK:       return:
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i1 [ true, [[RETURN]] ], [ false, [[THEN]] ]
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i1 [ false, [[THEN]] ], [ true, [[ENTRY:%.*]] ], [ true, [[ELSE]] ]
 ; CHECK-NEXT:    ret i1 [[RETVAL_0]]
 ;
 entry:
@@ -44,14 +44,14 @@ define i8 @switch_uncond(i8 %arg) {
 ; CHECK-NEXT:    unreachable
 ; CHECK:       bb:
 ; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br label [[BB2]]
+; CHECK-NEXT:    br label [[END]]
 ; CHECK:       bb1:
 ; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br label [[BB2]]
+; CHECK-NEXT:    br label [[END]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ 0, [[BB2]] ], [ 1, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ 1, [[ENTRY:%.*]] ], [ 0, [[BB3]] ], [ 0, [[BB1]] ], [ 0, [[BB2]] ]
 ; CHECK-NEXT:    ret i8 [[PHI]]
 ;
 entry:
diff --git a/llvm/test/Transforms/PhaseOrdering/thread-uncond-bb.ll b/llvm/test/Transforms/PhaseOrdering/thread-uncond-bb.ll
new file mode 100644
index 00000000000000..17146d7d5987fc
--- /dev/null
+++ b/llvm/test/Transforms/PhaseOrdering/thread-uncond-bb.ll
@@ -0,0 +1,62 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -O3 -S | FileCheck %s
+
+define i32 @thread_uncond_bb_cmp(i1 %c, i32 %v) {
+; CHECK-LABEL: define i32 @thread_uncond_bb_cmp(
+; CHECK-SAME: i1 [[C:%.*]], i32 [[V:%.*]]) local_unnamed_addr {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C]], label [[DO_END:%.*]], label [[IF_THEN:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    tail call void @dummy()
+; CHECK-NEXT:    br label [[DO_END]]
+; CHECK:       return:
+; CHECK-NEXT:    [[RETVAL:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[V]], [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL]]
+;
+entry:
+  br i1 %c, label %do.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  call void @dummy()
+  %tobool = icmp eq i32 %v, 0
+  br i1 %tobool, label %do.end, label %return
+
+do.end:                                           ; preds = %entry, %if.then
+  br label %return
+
+return:                                           ; preds = %if.then, %do.end
+  %retval = phi i32 [ 0, %do.end ], [ %v, %if.then ]
+  ret i32 %retval
+}
+
+define i32 @thread_uncond_bb_cmp_zext(i1 %c, i32 %v) {
+; CHECK-LABEL: define i32 @thread_uncond_bb_cmp_zext(
+; CHECK-SAME: i1 [[C:%.*]], i32 [[V:%.*]]) local_unnamed_addr {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C]], label [[DO_END:%.*]], label [[IF_THEN:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    tail call void @dummy()
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i32 [[V]], 0
+; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = zext i1 [[TOBOOL]] to i32
+; CHECK-NEXT:    br label [[DO_END]]
+; CHECK:       return:
+; CHECK-NEXT:    [[RETVAL:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SPEC_SELECT]], [[IF_THEN]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL]]
+;
+entry:
+  br i1 %c, label %do.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  call void @dummy()
+  %tobool = icmp eq i32 %v, 0
+  br i1 %tobool, label %do.end, label %return
+
+do.end:                                           ; preds = %entry, %if.then
+  br label %return
+
+return:                                           ; preds = %if.then, %do.end
+  %retval = phi i32 [ 0, %do.end ], [ 1, %if.then ]
+  ret i32 %retval
+}
+
+declare void @dummy()



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