Revert r315992 because of a found miscompilation failure

llvm-svn: 316164

2 files changed, 22 insertions, 43 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 4f5d69d77aa..225d0649c2e 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4083,14 +4083,6 @@ static SelectPatternResult matchMinMax(CmpInst::Predicate Pred,
                                        Value *CmpLHS, Value *CmpRHS,
                                        Value *TrueVal, Value *FalseVal,
                                        Value *&LHS, Value *&RHS) {
-  assert(!ICmpInst::isEquality(Pred) && "Expected not equality predicate only!");
-
-  // First, check if select has inverse order of what we will check below:
-  if (CmpRHS == FalseVal) {
-    std::swap(TrueVal, FalseVal);
-    Pred = CmpInst::getInversePredicate(Pred);
-  }
-
   // Assume success. If there's no match, callers should not use these anyway.
   LHS = TrueVal;
   RHS = FalseVal;
@@ -4103,30 +4095,26 @@ static SelectPatternResult matchMinMax(CmpInst::Predicate Pred,
 
     // (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1)
     if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) &&
-        C1->slt(*C2) &&
-        (Pred == CmpInst::ICMP_SLT || Pred == CmpInst::ICMP_SLE))
+        C1->slt(*C2) && Pred == CmpInst::ICMP_SLT)
       return {SPF_SMAX, SPNB_NA, false};
 
     // (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1)
     if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) &&
-        C1->sgt(*C2) &&
-        (Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE))
+        C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT)
       return {SPF_SMIN, SPNB_NA, false};
 
     // (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1)
     if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) &&
-        C1->ult(*C2) &&
-        (Pred == CmpInst::ICMP_ULT || Pred == CmpInst::ICMP_ULE))
+        C1->ult(*C2) && Pred == CmpInst::ICMP_ULT)
       return {SPF_UMAX, SPNB_NA, false};
 
     // (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1)
     if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) &&
-        C1->ugt(*C2) &&
-        (Pred == CmpInst::ICMP_UGT || Pred == CmpInst::ICMP_UGE))
+        C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT)
       return {SPF_UMIN, SPNB_NA, false};
   }
 
-  if (!CmpInst::isSigned(Pred))
+  if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT)
     return {SPF_UNKNOWN, SPNB_NA, false};
 
   // Z = X -nsw Y
@@ -4134,18 +4122,14 @@ static SelectPatternResult matchMinMax(CmpInst::Predicate Pred,
   // (X <s Y) ? 0 : Z ==> (Z <s 0) ? 0 : Z ==> SMAX(Z, 0)
   if (match(TrueVal, m_Zero()) &&
       match(FalseVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS))))
-    return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMIN
-                                                                     : SPF_SMAX,
-            SPNB_NA, false};
+    return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false};
 
   // Z = X -nsw Y
   // (X >s Y) ? Z : 0 ==> (Z >s 0) ? Z : 0 ==> SMAX(Z, 0)
   // (X <s Y) ? Z : 0 ==> (Z <s 0) ? Z : 0 ==> SMIN(Z, 0)
   if (match(FalseVal, m_Zero()) &&
       match(TrueVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS))))
-    return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMAX
-                                                                     : SPF_SMIN,
-            SPNB_NA, false};
+    return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false};
 
   if (!match(CmpRHS, m_APInt(C1)))
     return {SPF_UNKNOWN, SPNB_NA, false};
@@ -4157,15 +4141,14 @@ static SelectPatternResult matchMinMax(CmpInst::Predicate Pred,
     // Is the sign bit set?
     // (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX
     // (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN
-    if ((Pred == CmpInst::ICMP_SLT || Pred == CmpInst::ICMP_SLE) && *C1 == 0 &&
-        C2->isMaxSignedValue())
+    if (Pred == CmpInst::ICMP_SLT && *C1 == 0 && C2->isMaxSignedValue())
       return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};
 
     // Is the sign bit clear?
     // (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX
     // (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN
-    if ((Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) &&
-        C1->isAllOnesValue() && C2->isMinSignedValue())
+    if (Pred == CmpInst::ICMP_SGT && C1->isAllOnesValue() &&
+        C2->isMinSignedValue())
       return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};
   }
 
@@ -4174,17 +4157,13 @@ static SelectPatternResult matchMinMax(CmpInst::Predicate Pred,
   // (X <s C) ? ~X : ~C ==> (~X >s ~C) ? ~X : ~C ==> SMAX(~X, ~C)
   if (match(TrueVal, m_Not(m_Specific(CmpLHS))) &&
       match(FalseVal, m_APInt(C2)) && ~(*C1) == *C2)
-    return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMIN
-                                                                     : SPF_SMAX,
-            SPNB_NA, false};
+    return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false};
 
   // (X >s C) ? ~C : ~X ==> (~X <s ~C) ? ~C : ~X ==> SMAX(~C, ~X)
   // (X <s C) ? ~C : ~X ==> (~X >s ~C) ? ~C : ~X ==> SMIN(~C, ~X)
   if (match(FalseVal, m_Not(m_Specific(CmpLHS))) &&
       match(TrueVal, m_APInt(C2)) && ~(*C1) == *C2)
-    return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMAX
-                                                                     : SPF_SMIN,
-            SPNB_NA, false};
+    return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false};
 
   return {SPF_UNKNOWN, SPNB_NA, false};
 }
diff --git a/llvm/test/Transforms/InstCombine/minmax-fold.ll b/llvm/test/Transforms/InstCombine/minmax-fold.ll
index 397c6940d2d..0bf4719636d 100644
--- a/llvm/test/Transforms/InstCombine/minmax-fold.ll
+++ b/llvm/test/Transforms/InstCombine/minmax-fold.ll
@@ -404,8 +404,8 @@ define i32 @clamp_signed3(i32 %x) {
 ; CHECK-LABEL: @clamp_signed3(
 ; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[X:%.*]], 255
 ; CHECK-NEXT:    [[MIN:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 255
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i32 [[MIN]], 15
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[TMP1]], i32 [[MIN]], i32 15
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sgt i32 [[X]], 15
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP1]], i32 [[MIN]], i32 15
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp2 = icmp slt i32 %x, 255
@@ -421,8 +421,8 @@ define i32 @clamp_signed4(i32 %x) {
 ; CHECK-LABEL: @clamp_signed4(
 ; CHECK-NEXT:    [[CMP2:%.*]] = icmp sgt i32 [[X:%.*]], 15
 ; CHECK-NEXT:    [[MAX:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 15
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i32 [[MAX]], 255
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[TMP1]], i32 [[MAX]], i32 255
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp slt i32 [[X]], 255
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP1]], i32 [[MAX]], i32 255
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp2 = icmp sgt i32 %x, 15
@@ -472,8 +472,8 @@ define i32 @clamp_unsigned3(i32 %x) {
 ; CHECK-LABEL: @clamp_unsigned3(
 ; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i32 [[X:%.*]], 255
 ; CHECK-NEXT:    [[MIN:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 255
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt i32 [[MIN]], 15
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[TMP1]], i32 [[MIN]], i32 15
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ugt i32 [[X]], 15
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP1]], i32 [[MIN]], i32 15
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp2 = icmp ult i32 %x, 255
@@ -489,8 +489,8 @@ define i32 @clamp_unsigned4(i32 %x) {
 ; CHECK-LABEL: @clamp_unsigned4(
 ; CHECK-NEXT:    [[CMP2:%.*]] = icmp ugt i32 [[X:%.*]], 15
 ; CHECK-NEXT:    [[MAX:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 15
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i32 [[MAX]], 255
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[TMP1]], i32 [[MAX]], i32 255
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[X]], 255
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP1]], i32 [[MAX]], i32 255
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp2 = icmp ugt i32 %x, 15
@@ -523,8 +523,8 @@ define i32 @clamp_check_for_no_infinite_loop2(i32 %i) {
 ; CHECK-LABEL: @clamp_check_for_no_infinite_loop2(
 ; CHECK-NEXT:    [[CMP1:%.*]] = icmp sgt i32 [[I:%.*]], -255
 ; CHECK-NEXT:    [[SEL1:%.*]] = select i1 [[CMP1]], i32 [[I]], i32 -255
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i32 [[SEL1]], 0
-; CHECK-NEXT:    [[RES:%.*]] = select i1 [[TMP1]], i32 [[SEL1]], i32 0
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[I]], 0
+; CHECK-NEXT:    [[RES:%.*]] = select i1 [[CMP2]], i32 [[SEL1]], i32 0
 ; CHECK-NEXT:    ret i32 [[RES]]
 ;
   %cmp1 = icmp sgt i32 %i, -255