InstCombine: Simplify FoldICmpCstShrCst

This function was complicated by the fact that it tried to perform
canonicalizations that were already preformed by InstSimplify.  Remove
this extra code and move the tests over to InstSimplify.  Add asserts to
make sure our preconditions hold before we make any assumptions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220314 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index fec51aa5ec6d99988b152fb8147b83dd90ead2a0..2be03bd7f04359f57e290f09410d0b657f72002d 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1052,69 +1052,37 @@ Instruction *InstCombiner::FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,
   APInt AP1 = CI1->getValue();
   APInt AP2 = CI2->getValue();
 
-  if (!AP1) {
-    if (!AP2) {
-      // Both Constants are 0.
-      return getConstant(true);
-    }
-
-    if (cast<BinaryOperator>(Op)->isExact())
-      return getConstant(false);
-
-    if (AP2.isNegative()) {
-      // MSB is set, so a lshr with a large enough 'A' would be undefined.
-      return getConstant(false);
-    }
+  assert(AP2 != 0 && "Handled in InstSimplify");
+  assert(!AP2.isAllOnesValue() && "Handled in InstSimplify");
 
+  if (!AP1)
     // 'A' must be large enough to shift out the highest set bit.
     return getICmp(I.ICMP_UGT, A,
                    ConstantInt::get(A->getType(), AP2.logBase2()));
-  }
-
-  if (!AP2) {
-    // Shifting 0 by any value gives 0.
-    return getConstant(false);
-  }
 
-  bool IsAShr = isa<AShrOperator>(Op);
-  if (AP1 == AP2) {
-    if (AP1.isAllOnesValue() && IsAShr) {
-      // Arithmatic shift of -1 is always -1.
-      return getConstant(true);
-    }
+  if (AP1 == AP2)
     return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
-  }
-
-  bool IsNegative = false;
-  if (IsAShr) {
-    if (AP1.isNegative() != AP2.isNegative()) {
-      // Arithmetic shift will never change the sign.
-      return getConstant(false);
-    }
-    // Both the constants are negative, take their positive to calculate log.
-    if (AP1.isNegative()) {
-      if (AP1.slt(AP2))
-        // Right-shifting won't increase the magnitude.
-        return getConstant(false);
-      IsNegative = true;
-    }
-  }
 
-  if (!IsNegative && AP1.ugt(AP2))
-    // Right-shifting will not increase the value.
-    return getConstant(false);
+  bool IsAShr = isa<AShrOperator>(Op);
+  // If we are dealing with an arithmetic shift, both constants should agree in
+  // sign.  InstSimplify's SimplifyICmpInst range analysis is supposed to catch
+  // the cases when they disagree.
+  assert((!IsAShr || (AP1.isNegative() == AP2.isNegative() && AP1.sgt(AP2))) &&
+         "Handled in InstSimplify");
 
   // Get the distance between the highest bit that's set.
   int Shift;
-  if (IsNegative)
+  // Both the constants are negative, take their positive to calculate log.
+  if (IsAShr && AP1.isNegative())
     // Get the ones' complement of AP2 and AP1 when computing the distance.
     Shift = (~AP2).logBase2() - (~AP1).logBase2();
   else
     Shift = AP2.logBase2() - AP1.logBase2();
 
-  if (IsAShr ? AP1 == AP2.ashr(Shift) : AP1 == AP2.lshr(Shift))
-    return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
-
+  if (Shift > 0) {
+    if (IsAShr ? AP1 == AP2.ashr(Shift) : AP1 == AP2.lshr(Shift))
+      return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
+  }
   // Shifting const2 will never be equal to const1.
   return getConstant(false);
 }

diff --git a/test/Transforms/InstCombine/icmp-shr.ll b/test/Transforms/InstCombine/icmp-shr.ll
index 7562f24a35d847c0e075a4b8e33f53b773da7be1..52414b99cca7bca5577a9f98ba8537b3b7cc78b6 100644 (file)
--- a/test/Transforms/InstCombine/icmp-shr.ll
+++ b/test/Transforms/InstCombine/icmp-shr.ll
@@ -2,134 +2,6 @@
 
 target datalayout = "e-p:64:64:64-p1:16:16:16-p2:32:32:32-p3:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 
-; CHECK-LABEL: @exact_lshr_eq_both_zero
-; CHECK-NEXT: ret i1 true
-define i1 @exact_lshr_eq_both_zero(i8 %a) {
- %shr = lshr exact i8 0, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_eq_both_zero
-; CHECK-NEXT: ret i1 true
-define i1 @exact_ashr_eq_both_zero(i8 %a) {
- %shr = ashr exact i8 0, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_lshr_eq_both_zero
-; CHECK-NEXT: ret i1 true
-define i1 @nonexact_lshr_eq_both_zero(i8 %a) {
- %shr = lshr i8 0, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_ashr_eq_both_zero
-; CHECK-NEXT: ret i1 true
-define i1 @nonexact_ashr_eq_both_zero(i8 %a) {
- %shr = ashr i8 0, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lshr_ne_both_zero
-; CHECK-NEXT: ret i1 false
-define i1 @exact_lshr_ne_both_zero(i8 %a) {
- %shr = lshr exact i8 0, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_ne_both_zero
-; CHECK-NEXT: ret i1 false
-define i1 @exact_ashr_ne_both_zero(i8 %a) {
- %shr = ashr exact i8 0, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_lshr_ne_both_zero
-; CHECK-NEXT: ret i1 false
-define i1 @nonexact_lshr_ne_both_zero(i8 %a) {
- %shr = lshr i8 0, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_ashr_ne_both_zero
-; CHECK-NEXT: ret i1 false
-define i1 @nonexact_ashr_ne_both_zero(i8 %a) {
- %shr = ashr i8 0, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lshr_eq_last_zero
-; CHECK-NEXT: ret i1 false
-define i1 @exact_lshr_eq_last_zero(i8 %a) {
- %shr = lshr exact i8 128, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_eq_last_zero
-; CHECK-NEXT: ret i1 false
-define i1 @exact_ashr_eq_last_zero(i8 %a) {
- %shr = ashr exact i8 -128, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lshr_ne_last_zero
-; CHECK-NEXT: ret i1 true
-define i1 @exact_lshr_ne_last_zero(i8 %a) {
- %shr = lshr exact i8 128, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_ne_last_zero
-; CHECK-NEXT: ret i1 true
-define i1 @exact_ashr_ne_last_zero(i8 %a) {
- %shr = ashr exact i8 -128, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_lshr_eq_last_zero
-; CHECK-NEXT: ret i1 false
-define i1 @nonexact_lshr_eq_last_zero(i8 %a) {
- %shr = lshr i8 128, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_ashr_eq_last_zero
-; CHECK-NEXT: ret i1 false
-define i1 @nonexact_ashr_eq_last_zero(i8 %a) {
- %shr = ashr i8 -128, %a
- %cmp = icmp eq i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_lshr_ne_last_zero
-; CHECK-NEXT: ret i1 true
-define i1 @nonexact_lshr_ne_last_zero(i8 %a) {
- %shr = lshr i8 128, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_ashr_ne_last_zero
-; CHECK-NEXT: ret i1 true
-define i1 @nonexact_ashr_ne_last_zero(i8 %a) {
- %shr = ashr i8 -128, %a
- %cmp = icmp ne i8 %shr, 0
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @lshr_eq_msb_low_last_zero
 ; CHECK-NEXT: icmp ugt i8 %a, 6
 define i1 @lshr_eq_msb_low_last_zero(i8 %a) {
@@ -162,70 +34,6 @@ define i1 @ashr_ne_msb_low_second_zero(i8 %a) {
  ret i1 %cmp
 }
 
-; CHECK-LABEL: @lshr_eq_first_zero
-; CHECK-NEXT: ret i1 false
-define i1 @lshr_eq_first_zero(i8 %a) {
- %shr = lshr i8 0, %a
- %cmp = icmp eq i8 %shr, 2
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @ashr_eq_first_zero
-; CHECK-NEXT: ret i1 false
-define i1 @ashr_eq_first_zero(i8 %a) {
- %shr = ashr i8 0, %a
- %cmp = icmp eq i8 %shr, 2
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @lshr_ne_first_zero
-; CHECK-NEXT: ret i1 true
-define i1 @lshr_ne_first_zero(i8 %a) {
- %shr = lshr i8 0, %a
- %cmp = icmp ne i8 %shr, 2
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @ashr_ne_first_zero
-; CHECK-NEXT: ret i1 true
-define i1 @ashr_ne_first_zero(i8 %a) {
- %shr = ashr i8 0, %a
- %cmp = icmp ne i8 %shr, 2
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @ashr_eq_both_minus1
-; CHECK-NEXT: ret i1 true
-define i1 @ashr_eq_both_minus1(i8 %a) {
- %shr = ashr i8 -1, %a
- %cmp = icmp eq i8 %shr, -1
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @ashr_ne_both_minus1
-; CHECK-NEXT: ret i1 false
-define i1 @ashr_ne_both_minus1(i8 %a) {
- %shr = ashr i8 -1, %a
- %cmp = icmp ne i8 %shr, -1
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_eq_both_minus1
-; CHECK-NEXT: ret i1 true
-define i1 @exact_ashr_eq_both_minus1(i8 %a) {
- %shr = ashr exact i8 -1, %a
- %cmp = icmp eq i8 %shr, -1
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_ne_both_minus1
-; CHECK-NEXT: ret i1 false
-define i1 @exact_ashr_ne_both_minus1(i8 %a) {
- %shr = ashr exact i8 -1, %a
- %cmp = icmp ne i8 %shr, -1
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @ashr_eq_both_equal
 ; CHECK-NEXT: icmp eq i8 %a, 0
 define i1 @ashr_eq_both_equal(i8 %a) {
@@ -290,22 +98,6 @@ define i1 @exact_lshr_ne_both_equal(i8 %a) {
  ret i1 %cmp
 }
 
-; CHECK-LABEL: @exact_ashr_eq_opposite_msb
-; CHECK-NEXT: ret i1 false
-define i1 @exact_ashr_eq_opposite_msb(i8 %a) {
- %shr = ashr exact i8 -128, %a
- %cmp = icmp eq i8 %shr, 1
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @ashr_eq_opposite_msb
-; CHECK-NEXT: ret i1 false
-define i1 @ashr_eq_opposite_msb(i8 %a) {
- %shr = ashr i8 -128, %a
- %cmp = icmp eq i8 %shr, 1
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @exact_lshr_eq_opposite_msb
 ; CHECK-NEXT: icmp eq i8 %a, 7
 define i1 @exact_lshr_eq_opposite_msb(i8 %a) {
@@ -322,22 +114,6 @@ define i1 @lshr_eq_opposite_msb(i8 %a) {
  ret i1 %cmp
 }
 
-; CHECK-LABEL: @exact_ashr_ne_opposite_msb
-; CHECK-NEXT: ret i1 true
-define i1 @exact_ashr_ne_opposite_msb(i8 %a) {
- %shr = ashr exact i8 -128, %a
- %cmp = icmp ne i8 %shr, 1
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @ashr_ne_opposite_msb
-; CHECK-NEXT: ret i1 true
-define i1 @ashr_ne_opposite_msb(i8 %a) {
- %shr = ashr i8 -128, %a
- %cmp = icmp ne i8 %shr, 1
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @exact_lshr_ne_opposite_msb
 ; CHECK-NEXT: icmp ne i8 %a, 7
 define i1 @exact_lshr_ne_opposite_msb(i8 %a) {
@@ -354,70 +130,6 @@ define i1 @lshr_ne_opposite_msb(i8 %a) {
  ret i1 %cmp
 }
 
-; CHECK-LABEL: @exact_ashr_eq_shift_gt
-; CHECK-NEXT : ret i1 false
-define i1 @exact_ashr_eq_shift_gt(i8 %a) {
- %shr = ashr exact i8 -2, %a
- %cmp = icmp eq i8 %shr, -8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_ne_shift_gt
-; CHECK-NEXT : ret i1 true
-define i1 @exact_ashr_ne_shift_gt(i8 %a) {
- %shr = ashr exact i8 -2, %a
- %cmp = icmp ne i8 %shr, -8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_ashr_eq_shift_gt
-; CHECK-NEXT : ret i1 false
-define i1 @nonexact_ashr_eq_shift_gt(i8 %a) {
- %shr = ashr i8 -2, %a
- %cmp = icmp eq i8 %shr, -8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_ashr_ne_shift_gt
-; CHECK-NEXT : ret i1 true
-define i1 @nonexact_ashr_ne_shift_gt(i8 %a) {
- %shr = ashr i8 -2, %a
- %cmp = icmp ne i8 %shr, -8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lshr_eq_shift_gt
-; CHECK-NEXT: ret i1 false
-define i1 @exact_lshr_eq_shift_gt(i8 %a) {
- %shr = lshr exact i8 2, %a
- %cmp = icmp eq i8 %shr, 8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lshr_ne_shift_gt
-; CHECK-NEXT: ret i1 true
-define i1 @exact_lshr_ne_shift_gt(i8 %a) {
- %shr = lshr exact i8 2, %a
- %cmp = icmp ne i8 %shr, 8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_lshr_eq_shift_gt
-; CHECK-NEXT : ret i1 false
-define i1 @nonexact_lshr_eq_shift_gt(i8 %a) {
- %shr = lshr i8 2, %a
- %cmp = icmp eq i8 %shr, 8
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @nonexact_lshr_ne_shift_gt
-; CHECK-NEXT : ret i1 true
-define i1 @nonexact_lshr_ne_shift_gt(i8 %a) {
- %shr = ashr i8 2, %a
- %cmp = icmp ne i8 %shr, 8
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @exact_ashr_eq
 ; CHECK-NEXT: icmp eq i8 %a, 7
 define i1 @exact_ashr_eq(i8 %a) {
@@ -610,22 +322,6 @@ define i1 @nonexact_ashr_ne_noexactdiv(i8 %a) {
  ret i1 %cmp
 }
 
-; CHECK-LABEL: @exact_lshr_eq_noexactlog
-; CHECK-NEXT: ret i1 false
-define i1 @exact_lshr_eq_noexactlog(i8 %a) {
- %shr = lshr exact i8 90, %a
- %cmp = icmp eq i8 %shr, 30
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lshr_ne_noexactlog
-; CHECK-NEXT: ret i1 true
-define i1 @exact_lshr_ne_noexactlog(i8 %a) {
- %shr = lshr exact i8 90, %a
- %cmp = icmp ne i8 %shr, 30
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @nonexact_lshr_eq_noexactlog
 ; CHECK-NEXT: ret i1 false
 define i1 @nonexact_lshr_eq_noexactlog(i8 %a) {
@@ -642,22 +338,6 @@ define i1 @nonexact_lshr_ne_noexactlog(i8 %a) {
  ret i1 %cmp
 }
 
-; CHECK-LABEL: @exact_ashr_eq_noexactlog
-; CHECK-NEXT: ret i1 false
-define i1 @exact_ashr_eq_noexactlog(i8 %a) {
- %shr = ashr exact i8 -90, %a
- %cmp = icmp eq i8 %shr, -30
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_ashr_ne_noexactlog
-; CHECK-NEXT: ret i1 true
-define i1 @exact_ashr_ne_noexactlog(i8 %a) {
- %shr = ashr exact i8 -90, %a
- %cmp = icmp ne i8 %shr, -30
- ret i1 %cmp
-}
-
 ; CHECK-LABEL: @nonexact_ashr_eq_noexactlog
 ; CHECK-NEXT: ret i1 false
 define i1 @nonexact_ashr_eq_noexactlog(i8 %a) {

diff --git a/test/Transforms/InstSimplify/ashr-nop.ll b/test/Transforms/InstSimplify/ashr-nop.ll
deleted file mode 100644 (file)
index 0914d72..0000000
--- a/test/Transforms/InstSimplify/ashr-nop.ll
+++ /dev/null
@@ -1,10 +0,0 @@
-; RUN: opt < %s -instsimplify -S | FileCheck %s
-
-; CHECK-LABEL: @foo
-; CHECK-NOT: ashr
-define i32 @foo(i32 %x) {
- %o = and i32 %x, 1
- %n = add i32 %o, -1
- %t = ashr i32 %n, 17
- ret i32 %t
-}

diff --git a/test/Transforms/InstSimplify/shr-nop.ll b/test/Transforms/InstSimplify/shr-nop.ll
new file mode 100644 (file)
index 0000000..86917ad
--- /dev/null
+++ b/test/Transforms/InstSimplify/shr-nop.ll
@@ -0,0 +1,332 @@
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+; CHECK-LABEL: @foo
+; CHECK:      %[[and:.*]] = and i32 %x, 1
+; CHECK-NEXT: %[[add:.*]] = add i32 %[[and]], -1
+; CHECK-NEXT: ret i32 %[[add]]
+define i32 @foo(i32 %x) {
+ %o = and i32 %x, 1
+ %n = add i32 %o, -1
+ %t = ashr i32 %n, 17
+ ret i32 %t
+}
+
+; CHECK-LABEL: @exact_lshr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_eq_both_zero(i8 %a) {
+ %shr = lshr exact i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_eq_both_zero(i8 %a) {
+ %shr = ashr exact i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_ashr_eq_both_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_ne_both_zero(i8 %a) {
+ %shr = lshr exact i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_ne_both_zero(i8 %a) {
+ %shr = ashr exact i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_lshr_ne_both_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_ashr_ne_both_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_last_zero(i8 %a) {
+ %shr = lshr exact i8 128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_last_zero(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_lshr_eq_both_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_last_zero(i8 %a) {
+ %shr = lshr exact i8 128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_last_zero(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_lshr_eq_last_zero(i8 %a) {
+ %shr = lshr i8 128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_ashr_eq_last_zero(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_lshr_ne_last_zero(i8 %a) {
+ %shr = lshr i8 128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_ashr_ne_last_zero(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_eq_first_zero
+; CHECK-NEXT: ret i1 false
+define i1 @lshr_eq_first_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp eq i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_first_zero
+; CHECK-NEXT: ret i1 false
+define i1 @ashr_eq_first_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp eq i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_ne_first_zero
+; CHECK-NEXT: ret i1 true
+define i1 @lshr_ne_first_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp ne i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_first_zero
+; CHECK-NEXT: ret i1 true
+define i1 @ashr_ne_first_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp ne i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_both_minus1
+; CHECK-NEXT: ret i1 true
+define i1 @ashr_eq_both_minus1(i8 %a) {
+ %shr = ashr i8 -1, %a
+ %cmp = icmp eq i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_both_minus1
+; CHECK-NEXT: ret i1 false
+define i1 @ashr_ne_both_minus1(i8 %a) {
+ %shr = ashr i8 -1, %a
+ %cmp = icmp ne i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_both_minus1
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_eq_both_minus1(i8 %a) {
+ %shr = ashr exact i8 -1, %a
+ %cmp = icmp eq i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_both_minus1
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_ne_both_minus1(i8 %a) {
+ %shr = ashr exact i8 -1, %a
+ %cmp = icmp ne i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_opposite_msb
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_opposite_msb(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_noexactlog
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_noexactlog(i8 %a) {
+ %shr = ashr exact i8 -90, %a
+ %cmp = icmp eq i8 %shr, -30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_opposite_msb
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_opposite_msb(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_opposite_msb
+; CHECK-NEXT: ret i1 false
+define i1 @ashr_eq_opposite_msb(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_opposite_msb
+; CHECK-NEXT: ret i1 true
+define i1 @ashr_ne_opposite_msb(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_shift_gt
+; CHECK-NEXT : ret i1 false
+define i1 @exact_ashr_eq_shift_gt(i8 %a) {
+ %shr = ashr exact i8 -2, %a
+ %cmp = icmp eq i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_shift_gt
+; CHECK-NEXT : ret i1 true
+define i1 @exact_ashr_ne_shift_gt(i8 %a) {
+ %shr = ashr exact i8 -2, %a
+ %cmp = icmp ne i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_shift_gt
+; CHECK-NEXT : ret i1 false
+define i1 @nonexact_ashr_eq_shift_gt(i8 %a) {
+ %shr = ashr i8 -2, %a
+ %cmp = icmp eq i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_shift_gt
+; CHECK-NEXT : ret i1 true
+define i1 @nonexact_ashr_ne_shift_gt(i8 %a) {
+ %shr = ashr i8 -2, %a
+ %cmp = icmp ne i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_shift_gt
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_shift_gt(i8 %a) {
+ %shr = lshr exact i8 2, %a
+ %cmp = icmp eq i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_shift_gt
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_shift_gt(i8 %a) {
+ %shr = lshr exact i8 2, %a
+ %cmp = icmp ne i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_shift_gt
+; CHECK-NEXT : ret i1 false
+define i1 @nonexact_lshr_eq_shift_gt(i8 %a) {
+ %shr = lshr i8 2, %a
+ %cmp = icmp eq i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_shift_gt
+; CHECK-NEXT : ret i1 true
+define i1 @nonexact_lshr_ne_shift_gt(i8 %a) {
+ %shr = ashr i8 2, %a
+ %cmp = icmp ne i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_noexactlog
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_noexactlog(i8 %a) {
+ %shr = ashr exact i8 -90, %a
+ %cmp = icmp ne i8 %shr, -30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_noexactlog
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_noexactlog(i8 %a) {
+ %shr = lshr exact i8 90, %a
+ %cmp = icmp eq i8 %shr, 30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_noexactlog
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_noexactlog(i8 %a) {
+ %shr = lshr exact i8 90, %a
+ %cmp = icmp ne i8 %shr, 30
+ ret i1 %cmp
+}