Index: llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
===================================================================
--- llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
+++ llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
@@ -511,6 +511,10 @@
   bool matchFunnelShiftToRotate(MachineInstr &MI);
   void applyFunnelShiftToRotate(MachineInstr &MI);
 
+  /// \return true if a G_ICMP can be replaced with its LHS.
+  bool matchReplaceICmpWithLHS(MachineInstr &MI);
+  bool applyReplaceICmpWithLHS(MachineInstr &MI);
+
   /// Try to transform \p MI by using all of the above
   /// combine functions. Returns true if changed.
   bool tryCombine(MachineInstr &MI);
Index: llvm/include/llvm/Target/GlobalISel/Combine.td
===================================================================
--- llvm/include/llvm/Target/GlobalISel/Combine.td
+++ llvm/include/llvm/Target/GlobalISel/Combine.td
@@ -605,6 +605,13 @@
   (apply [{ Helper.applyFunnelShiftToRotate(*${root}); }])
 >;
 
+def replace_icmp_with_lhs: GICombineRule<
+  (defs root:$root),
+  (match (wip_match_opcode G_ICMP):$root,
+    [{ return Helper.matchReplaceICmpWithLHS(*${root}); }]),
+  (apply [{ Helper.applyReplaceICmpWithLHS(*${root}); }])
+>;
+
 def funnel_shift_combines : GICombineGroup<[funnel_shift_to_rotate]>;
 
 // FIXME: These should use the custom predicate feature once it lands.
@@ -626,7 +633,7 @@
 
 def known_bits_simplifications : GICombineGroup<[
   redundant_and, redundant_sext_inreg, redundant_or, urem_pow2_to_mask,
-  zext_trunc_fold]>;
+  zext_trunc_fold, replace_icmp_with_lhs]>;
 
 def width_reduction_combines : GICombineGroup<[reduce_shl_of_extend]>;
 
Index: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -3894,6 +3894,61 @@
   Observer.changedInstr(MI);
 }
 
+bool CombinerHelper::matchReplaceICmpWithLHS(MachineInstr &MI) {
+  // When we have
+  //
+  // %c = icmp eq/ne %x, cst
+  //
+  // If we know that true == 1 and false == 0, and we know that %x is either 0
+  // or 1, then
+  //
+  // %c = icmp eq %x, 1 -> %x
+  // %c = icmp ne %x, 0 -> %x
+  assert(MI.getOpcode() == TargetOpcode::G_ICMP);
+  assert(KB && "Combiner should have KnownBits!");
+  auto Pred = static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate());
+  if (!ICmpInst::isEquality(Pred))
+    return false;
+  Register LHS = MI.getOperand(2).getReg();
+  bool IsVector = MRI.getType(LHS).isVector();
+  // Need to have ZeroOrOneBooleanContent, otherwise we can't tell if we have
+  // exactly one of true/false via KB.
+  if (getICmpTrueVal(getTargetLowering(), IsVector,
+                     /*IsFP = */ false) != 1)
+    return false;
+  int64_t ValToMatch = Pred == CmpInst::ICMP_EQ ? 1 : 0;
+  Register RHS = MI.getOperand(3).getReg();
+  if (IsVector) {
+    // FIXME: Once mi_match handles splats/vector constants, we can simplify
+    // this.
+    auto MaybeSplat = getBuildVectorConstantSplat(*MRI.getVRegDef(RHS), MRI);
+    if (!MaybeSplat || *MaybeSplat != ValToMatch)
+      return false;
+  } else if (!mi_match(RHS, MRI, m_SpecificICst(ValToMatch)))
+    return false;
+
+  // Check if the value is known to be exactly one of 0 (false) or 1 (true).
+  auto KnownLHS = KB->getKnownBits(LHS);
+  return KnownLHS.getMinValue() == 0 && KnownLHS.getMaxValue() == 1;
+}
+
+bool CombinerHelper::applyReplaceICmpWithLHS(MachineInstr &MI) {
+  assert(MI.getOpcode() == TargetOpcode::G_ICMP);
+  // Apply:
+  //   %c = icmp eq %x, 1 -> %x
+  //   %c = icmp ne %x, 0 -> %x
+  Register LHS = MI.getOperand(2).getReg();
+  Register Dst = MI.getOperand(0).getReg();
+  if (MRI.getType(LHS) == MRI.getType(Dst))
+    return replaceSingleDefInstWithOperand(MI, 2);
+  // Note that we assume that we have ZeroOrOneBooleanContents, so ZExting is
+  // always correct here.
+  Builder.setInstrAndDebugLoc(MI);
+  Builder.buildZExtOrTrunc(Dst, LHS);
+  MI.eraseFromParent();
+  return true;
+}
+
 bool CombinerHelper::tryCombine(MachineInstr &MI) {
   if (tryCombineCopy(MI))
     return true;
Index: llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-simplify-cmp-known-true-false.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-simplify-cmp-known-true-false.mir
@@ -0,0 +1,283 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple aarch64-apple-ios  -run-pass=aarch64-prelegalizer-combiner --aarch64prelegalizercombinerhelper-only-enable-rule="replace_icmp_with_lhs" %s -o - -verify-machineinstrs | FileCheck %s
+# REQUIRES: asserts
+
+# Check that we can combine patterns like this:
+#  %c = icmp eq %x, 1 -> %x
+#  %c = icmp ne %x, 0 -> %x
+
+...
+---
+name: eq_one
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: eq_one
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s64) = COPY $x0
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: %cmp:_(s1) = G_TRUNC %lhs(s64)
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = COPY $x0
+    %one:_(s64) = G_CONSTANT i64 1
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s1) = G_ICMP intpred(eq), %lhs(s64), %one
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name: ne_zero
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $w0
+    ; CHECK-LABEL: name: ne_zero
+    ; CHECK: liveins: $w0
+    ; CHECK: %x:_(s64) = G_IMPLICIT_DEF
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: %cmp:_(s1) = G_TRUNC %lhs(s64)
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = G_IMPLICIT_DEF
+    %one:_(s64) = G_CONSTANT i64 1
+    %zero:_(s64) = G_CONSTANT i64 0
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %zero
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name: eq_zero
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $w0
+    ; CHECK-LABEL: name: eq_zero
+    ; CHECK: liveins: $w0
+    ; CHECK: %x:_(s64) = G_IMPLICIT_DEF
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %zero:_(s64) = G_CONSTANT i64 0
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: %cmp:_(s1) = G_ICMP intpred(eq), %lhs(s64), %zero
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = G_IMPLICIT_DEF
+    %one:_(s64) = G_CONSTANT i64 1
+    %zero:_(s64) = G_CONSTANT i64 0
+    ; Mask to 0 or 1
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s1) = G_ICMP intpred(eq), %lhs(s64), %zero
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name: matching_size
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; Apply, but don't truncate or zero extend.
+    ; CHECK-LABEL: name: matching_size
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s64) = COPY $x0
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: $x0 = COPY %lhs(s64)
+    ; CHECK: RET_ReallyLR implicit $x0
+    %x:_(s64) = COPY $x0
+    %one:_(s64) = G_CONSTANT i64 1
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s64) = G_ICMP intpred(eq), %lhs(s64), %one
+    $x0 = COPY %cmp(s64)
+    RET_ReallyLR implicit $x0
+...
+---
+name: cmp_larger
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; Apply, and zero extend.
+    ; CHECK-LABEL: name: cmp_larger
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s32) = COPY $w0
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %lhs:_(s32) = G_AND %x, %one
+    ; CHECK: %cmp:_(s64) = G_ZEXT %lhs(s32)
+    ; CHECK: $x0 = COPY %cmp(s64)
+    ; CHECK: RET_ReallyLR implicit $x0
+    %x:_(s32) = COPY $w0
+    %one:_(s32) = G_CONSTANT i32 1
+    %lhs:_(s32) = G_AND %x, %one
+    %cmp:_(s64) = G_ICMP intpred(eq), %lhs(s32), %one
+    $x0 = COPY %cmp(s64)
+    RET_ReallyLR implicit $x0
+...
+---
+name: ne_one
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: ne_one
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s64) = COPY $x0
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %one
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = COPY $x0
+    %one:_(s64) = G_CONSTANT i64 1
+    ; Mask to 0 or 1
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %one
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name: wrong_cst_ne
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: wrong_cst_ne
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s64) = COPY $x0
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %cst:_(s64) = G_CONSTANT i64 2
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %cst
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = COPY $x0
+    %one:_(s64) = G_CONSTANT i64 1
+    %cst:_(s64) = G_CONSTANT i64 2
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %cst
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name: wrong_cst_eq
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: wrong_cst_eq
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s64) = COPY $x0
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %cst:_(s64) = G_CONSTANT i64 -1
+    ; CHECK: %lhs:_(s64) = G_AND %x, %one
+    ; CHECK: %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %cst
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = COPY $x0
+    %one:_(s64) = G_CONSTANT i64 1
+    %cst:_(s64) = G_CONSTANT i64 -1
+    %lhs:_(s64) = G_AND %x, %one
+    %cmp:_(s1) = G_ICMP intpred(ne), %lhs(s64), %cst
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
+...
+---
+name: dont_combine_vector_neg_one
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; AArch64 has -1 as true when we have a vector. Don't combine.
+
+    ; CHECK-LABEL: name: dont_combine_vector_neg_one
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(<2 x s32>) = COPY $x0
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %neg_one:_(s32) = G_CONSTANT i32 -1
+    ; CHECK: %neg_one_vec:_(<2 x s32>) = G_BUILD_VECTOR %neg_one(s32), %neg_one(s32)
+    ; CHECK: %cmp:_(<2 x s1>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %neg_one_vec
+    ; CHECK: %ext:_(<2 x s32>) = G_ANYEXT %cmp(<2 x s1>)
+    ; CHECK: $x0 = COPY %ext(<2 x s32>)
+    ; CHECK: RET_ReallyLR implicit $x0
+    %x:_(<2 x s32>) = COPY $x0
+
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+
+    %neg_one:_(s32) = G_CONSTANT i32 -1
+    %neg_one_vec:_(<2 x s32>) = G_BUILD_VECTOR %neg_one, %neg_one
+    %cmp:_(<2 x s1>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %neg_one_vec
+    %ext:_(<2 x s32>) = G_ANYEXT %cmp
+    $x0 = COPY %ext(<2 x s32>)
+    RET_ReallyLR implicit $x0
+...
+---
+name: dont_combine_vector_one
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; 1 is not the true value for vectors on AArch64. Don't combine.
+
+    ; CHECK-LABEL: name: dont_combine_vector_one
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(<2 x s32>) = COPY $x0
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %cmp:_(<2 x s1>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %one_vec
+    ; CHECK: %ext:_(<2 x s32>) = G_ANYEXT %cmp(<2 x s1>)
+    ; CHECK: $x0 = COPY %ext(<2 x s32>)
+    ; CHECK: RET_ReallyLR implicit $x0
+    %x:_(<2 x s32>) = COPY $x0
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %cmp:_(<2 x s1>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %one_vec
+    %ext:_(<2 x s32>) = G_ANYEXT %cmp
+    $x0 = COPY %ext(<2 x s32>)
+    RET_ReallyLR implicit $x0
+...
+---
+name: val_not_between_zero_and_one
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: val_not_between_zero_and_one
+    ; CHECK: liveins: $x0
+    ; CHECK: %x:_(s64) = COPY $x0
+    ; CHECK: %one:_(s64) = G_CONSTANT i64 1
+    ; CHECK: %three:_(s64) = G_CONSTANT i64 3
+    ; CHECK: %lhs:_(s64) = G_AND %x, %three
+    ; CHECK: %cmp:_(s1) = G_ICMP intpred(eq), %lhs(s64), %one
+    ; CHECK: %ext:_(s32) = G_ANYEXT %cmp(s1)
+    ; CHECK: $w0 = COPY %ext(s32)
+    ; CHECK: RET_ReallyLR implicit $w0
+    %x:_(s64) = COPY $x0
+    %one:_(s64) = G_CONSTANT i64 1
+    %three:_(s64) = G_CONSTANT i64 3
+    %lhs:_(s64) = G_AND %x, %three
+    %cmp:_(s1) = G_ICMP intpred(eq), %lhs(s64), %one
+    %ext:_(s32) = G_ANYEXT %cmp
+    $w0 = COPY %ext(s32)
+    RET_ReallyLR implicit $w0
Index: llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizercombiner-simplify-cmp-known-true-false.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizercombiner-simplify-cmp-known-true-false.mir
@@ -0,0 +1,158 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -run-pass=amdgpu-prelegalizer-combiner --amdgpuprelegalizercombinerhelper-only-enable-rule="replace_icmp_with_lhs" -verify-machineinstrs -o - %s | FileCheck %s
+# REQUIRES: asserts
+
+# Check that we can combine patterns like this:
+#  %c = icmp eq %x, 1 -> %x
+#  %c = icmp ne %x, 0 -> %x
+
+...
+---
+name: eq_vector
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: eq_vector
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK: %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %cmp:_(<2 x s1>) = G_TRUNC %lhs(<2 x s32>)
+    ; CHECK: %ext:_(<2 x s32>) = G_ANYEXT %cmp(<2 x s1>)
+    ; CHECK: $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+    %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %cmp:_(<2 x s1>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %one_vec
+    %ext:_(<2 x s32>) = G_ANYEXT %cmp
+    $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+
+...
+---
+name: ne_vector
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: ne_vector
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK: %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %cmp:_(<2 x s1>) = G_TRUNC %lhs(<2 x s32>)
+    ; CHECK: %ext:_(<2 x s32>) = G_ANYEXT %cmp(<2 x s1>)
+    ; CHECK: $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+    %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %zero:_(s32) = G_CONSTANT i32 0
+    %zero_vec:_(<2 x s32>) = G_BUILD_VECTOR %zero, %zero
+    %cmp:_(<2 x s1>) = G_ICMP intpred(ne), %lhs(<2 x s32>), %zero_vec
+    %ext:_(<2 x s32>) = G_ANYEXT %cmp
+    $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+
+...
+---
+name: no_trunc
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+
+    ; Don't truncate when %cmp and %lhs are the same size.
+
+    ; CHECK-LABEL: name: no_trunc
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK: %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: $vgpr0_vgpr1 = COPY %lhs(<2 x s32>)
+    %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %cmp:_(<2 x s32>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %one_vec
+    $vgpr0_vgpr1 = COPY %cmp(<2 x s32>)
+
+...
+---
+name: zext
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+
+    ; %cmp is larger than %lhs, so we should zero-extend
+
+    ; CHECK-LABEL: name: zext
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK: %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %cmp:_(<2 x s64>) = G_ZEXT %lhs(<2 x s32>)
+    ; CHECK: $vgpr0_vgpr1_vgpr2_vgpr3 = COPY %cmp(<2 x s64>)
+    %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %cmp:_(<2 x s64>) = G_ICMP intpred(eq), %lhs(<2 x s32>), %one_vec
+    $vgpr0_vgpr1_vgpr2_vgpr3 = COPY %cmp(<2 x s64>)
+
+...
+---
+name: wrong_cst
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: wrong_cst
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK: %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %neg_one:_(s32) = G_CONSTANT i32 -1
+    ; CHECK: %neg_one_vec:_(<2 x s32>) = G_BUILD_VECTOR %neg_one(s32), %neg_one(s32)
+    ; CHECK: %cmp:_(<2 x s1>) = G_ICMP intpred(ne), %lhs(<2 x s32>), %neg_one_vec
+    ; CHECK: %ext:_(<2 x s32>) = G_ANYEXT %cmp(<2 x s1>)
+    ; CHECK: $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+    %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %neg_one:_(s32) = G_CONSTANT i32 -1
+    %neg_one_vec:_(<2 x s32>) = G_BUILD_VECTOR %neg_one, %neg_one
+    %cmp:_(<2 x s1>) = G_ICMP intpred(ne), %lhs(<2 x s32>), %neg_one_vec
+    %ext:_(<2 x s32>) = G_ANYEXT %cmp
+    $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+
+...
+---
+name: wrong_pred
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: wrong_pred
+    ; CHECK: liveins: $vgpr0_vgpr1
+    ; CHECK: %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    ; CHECK: %one:_(s32) = G_CONSTANT i32 1
+    ; CHECK: %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one(s32), %one(s32)
+    ; CHECK: %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    ; CHECK: %cmp:_(<2 x s1>) = G_ICMP intpred(sge), %lhs(<2 x s32>), %one_vec
+    ; CHECK: %ext:_(<2 x s32>) = G_ANYEXT %cmp(<2 x s1>)
+    ; CHECK: $vgpr0_vgpr1 = COPY %ext(<2 x s32>)
+    %x:_(<2 x s32>) = COPY $vgpr0_vgpr1
+    %one:_(s32) = G_CONSTANT i32 1
+    %one_vec:_(<2 x s32>) = G_BUILD_VECTOR %one, %one
+    %lhs:_(<2 x s32>) = G_AND %x, %one_vec
+    %cmp:_(<2 x s1>) = G_ICMP intpred(sge), %lhs(<2 x s32>), %one_vec
+    %ext:_(<2 x s32>) = G_ANYEXT %cmp
+    $vgpr0_vgpr1 = COPY %ext(<2 x s32>)