[InstCombine] Teach foldOrOfICmps to allow icmp eq MIN_INT/MAX to be part of a range comparision. Similar for foldAndOfICmps

[craig.topper]

Summary

We can treat icmp eq X, MIN_UINT as icmp ule X, MIN_UINT and allow
it to merge with icmp ugt X, C. Similar for the other constants.

We can do simliar for icmp ne X, (U)INT_MIN/MAX in foldAndOfICmps. And we already handled UINT_MIN there.

Fixes PR42691.

[craig.topper]

Rebase with the tests pre-commited

[craig.topper]

Rebase after making one of the tests better

[nikic]

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

2262 ↗

(On Diff #210895)

ULE -> SLE

llvm/test/Transforms/InstCombine/and-or-icmps.ll

316 ↗

(On Diff #210895)

This seems like a weird choice that the range check code is making. We could also generate

%x.off = add i32 %x, 1
%c = icmp ult i32 %x.off, -2147483646

with smaller constants.

[craig.topper]

Fix copy/paste mistake in comment

[craig.topper]

Also update foldAndOfICmps to handle not equal (U)INT_MIN/MAX

[craig.topper]

llvm/test/Transforms/InstCombine/and-or-icmps.ll

316 ↗

(On Diff #210895)

Is this something this patch should address?

[lebedev.ri]

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

1208–1211 ↗

(On Diff #211017)

Ok, https://rise4fun.com/Alive/VUp
Comment does not specify the precondition that C != INT_MIN
I'm guessing that case is handled elsewhere?

1226–1229 ↗

(On Diff #211017)

Update comment please: X u> 13 & X != UINT_MAX -> (X-(C+1)) u< UINT_MAX-(C+1)
https://rise4fun.com/Alive/qt2, ok
Comment does not specify the precondition that C != UINT_MAX
I'm guessing that case is handled elsewhere?

1244–1247 ↗

(On Diff #211017)

Fix comment please: X s> 13 & X != INT_MAX -> (X-(C+1))) u< INT_MAX-(C+1)
https://rise4fun.com/Alive/hZlO, ok
Comment does not specify the precondition that C != INT_MAX
I'm guessing that case is handled elsewhere?

2269–2309 ↗

(On Diff #211017)

Can you please add actual formulas here as comments?

llvm/test/Transforms/InstCombine/and-or-icmps.ll

316 ↗

(On Diff #210895)

Is this something this patch should address?

I'm going to go with no. That is a separate fold.

[craig.topper]

Clean up comments in the new code. And a few minor fixes to the comments in the existing code. Probably should rewrite them to use C instead of specific numbers, but for now I just fixed them to not be completely incorrect about what insertRangeTest does.

[craig.topper]

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

1226–1229 ↗

(On Diff #211017)

There's an earlier assert above this switch that says LHSC != RHSC which would ensure C can't be UINT_MAX.

[lebedev.ri]

Ok, LGTM, thank you.

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

2269–2272 ↗

(On Diff #211579)

https://rise4fun.com/Alive/3RLT ok

2276–2279 ↗

(On Diff #211579)

https://rise4fun.com/Alive/1ri ok

2289–2292 ↗

(On Diff #211579)

https://rise4fun.com/Alive/zq4 ok

2304–2308 ↗

(On Diff #211579)

https://rise4fun.com/Alive/xb2 ok

llvm/test/Transforms/InstCombine/and-or-icmps.ll

316 ↗

(On Diff #210895)

This might warrant filing an issue to track though.

llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

Value *InstCombiner::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
   case ICmpInst::ICMP_NE:
     switch (PredR) {
     default:
       llvm_unreachable("Unknown integer condition code!");
     case ICmpInst::ICMP_ULT:
       // (X != 13 & X u< 14) -> X < 13
       if (LHSC->getValue() == (RHSC->getValue() - 1))
         return Builder.CreateICmpULT(LHS0, LHSC);
-      if (LHSC->isZero()) // (X != 0 & X u< 14) -> X-1 u< 13
+      if (LHSC->isZero()) // (X != 0 & X u< C) -> X-1 u< C-1
         return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
                                false, true);
       break; // (X != 13 & X u< 15) -> no change
     case ICmpInst::ICMP_SLT:
       // (X != 13 & X s< 14) -> X < 13
       if (LHSC->getValue() == (RHSC->getValue() - 1))
         return Builder.CreateICmpSLT(LHS0, LHSC);
-      break;                 // (X != 13 & X s< 15) -> no change
+      // (X != INT_MIN & X s< C) -> X-(INT_MIN+1) u< (C-(INT_MIN+1))
+      if (LHSC->isMinValue(true))
+        return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
+                               true, true);
+      break; // (X != 13 & X s< 15) -> no change
     case ICmpInst::ICMP_NE:
       // Potential folds for this case should already be handled.
       break;
     }
     break;
   case ICmpInst::ICMP_UGT:
     switch (PredR) {
     default:
       llvm_unreachable("Unknown integer condition code!");
     case ICmpInst::ICMP_NE:
       // (X u> 13 & X != 14) -> X u> 14
       if (RHSC->getValue() == (LHSC->getValue() + 1))
         return Builder.CreateICmp(PredL, LHS0, RHSC);
+      // X u> C & X != UINT_MAX -> (X-(C+1)) u< UINT_MAX-(C+1)
+      if (RHSC->isMaxValue(false))
+        return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
+                               false, true);
       break;                 // (X u> 13 & X != 15) -> no change
-    case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
+    case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) u< 1
       return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
                              false, true);
     }
     break;
   case ICmpInst::ICMP_SGT:
     switch (PredR) {
     default:
       llvm_unreachable("Unknown integer condition code!");
     case ICmpInst::ICMP_NE:
       // (X s> 13 & X != 14) -> X s> 14
       if (RHSC->getValue() == (LHSC->getValue() + 1))
         return Builder.CreateICmp(PredL, LHS0, RHSC);
+      // X s> C & X != INT_MAX -> (X-(C+1)) u< INT_MAX-(C+1)
+      if (RHSC->isMaxValue(true))
+        return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
+                               true, true);
       break;                 // (X s> 13 & X != 15) -> no change
-    case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
+    case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) u< 1
       return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true,
                              true);
     }
     break;
   }
 
   return nullptr;
 }
default:
     llvm_unreachable("Unknown integer condition code!");
   case ICmpInst::ICMP_EQ:
     switch (PredR) {
     default:
       llvm_unreachable("Unknown integer condition code!");
     case ICmpInst::ICMP_EQ:
       // Potential folds for this case should already be handled.
       break;
-    case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
-    case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
+    case ICmpInst::ICMP_UGT:
+      // (X == 0 || X u> C) -> (X-1) u>= C
+      if (LHSC->isMinValue(false))
+        return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
+                               false, false);
+      // (X == 13 | X u> 14) -> no change
+      break;
+    case ICmpInst::ICMP_SGT:
+      // (X == INT_MIN || X s> C) -> (X-(INT_MIN+1)) u>= C-INT_MIN
+      if (LHSC->isMinValue(true))
+        return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
+                               true, false);
+      // (X == 13 | X s> 14) -> no change
       break;
     }
     break;
   case ICmpInst::ICMP_ULT:
     switch (PredR) {
     default:
       llvm_unreachable("Unknown integer condition code!");
     case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
+      // (X u< C || X == UINT_MAX) => (X-C) u>= UINT_MAX-C
+      if (RHSC->isMaxValue(false))
+        return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
+                               false, false);
       break;
     case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
       assert(!RHSC->isMaxValue(false) && "Missed icmp simplification");
       return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1,
                              false, false);
     }
     break;
   case ICmpInst::ICMP_SLT:
     switch (PredR) {
     default:
       llvm_unreachable("Unknown integer condition code!");
-    case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
+    case ICmpInst::ICMP_EQ:
+      // (X s< C || X == INT_MAX) => (X-C) u>= INT_MAX-C
+      if (RHSC->isMaxValue(true))
+        return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
+                               true, false);
+      // (X s< 13 | X == 14) -> no change
       break;
-    case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
+    case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) u> 2
       assert(!RHSC->isMaxValue(true) && "Missed icmp simplification");
       return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true,
                              false);
     }
     break;
   }
   return nullptr;
 }

llvm/trunk/test/Transforms/InstCombine/and-or-icmps.ll

;
   store i16 %B33, i16* undef
   store i1 %C18, i1* undef
   store i1* %G26, i1** undef
   ret void
 }
 
 define i1 @PR42691_1(i32 %x) {
 ; CHECK-LABEL: @PR42691_1(
-; CHECK-NEXT:    [[C1:%.*]] = icmp slt i32 %x, 0
-; CHECK-NEXT:    [[C2:%.*]] = icmp eq i32 %x, 2147483647
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt i32 %x, 2147483646
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp slt i32 %x, 0
   %c2 = icmp eq i32 %x, 2147483647
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_2(i32 %x) {
 ; CHECK-LABEL: @PR42691_2(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i32 %x, -2
 ; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp ult i32 %x, 2147483648
   %c2 = icmp eq i32 %x, 4294967295
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_3(i32 %x) {
 ; CHECK-LABEL: @PR42691_3(
-; CHECK-NEXT:    [[C1:%.*]] = icmp sgt i32 %x, -1
-; CHECK-NEXT:    [[C2:%.*]] = icmp eq i32 %x, -2147483648
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i32 %x, -2147483647
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp sge i32 %x, 0
   %c2 = icmp eq i32 %x, -2147483648
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_4(i32 %x) {
 ; CHECK-LABEL: @PR42691_4(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i32 %x, 1
 ; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp uge i32 %x, 2147483648
   %c2 = icmp eq i32 %x, 0
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_5(i32 %x) {
 ; CHECK-LABEL: @PR42691_5(
-; CHECK-NEXT:    [[C1:%.*]] = icmp slt i32 %x, 1
-; CHECK-NEXT:    [[C2:%.*]] = icmp eq i32 %x, 2147483647
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[X_OFF:%.*]] = add i32 %x, -1
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt i32 [[X_OFF]], 2147483645
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp slt i32 %x, 1
   %c2 = icmp eq i32 %x, 2147483647
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_6(i32 %x) {
 ; CHECK-LABEL: @PR42691_6(
-; CHECK-NEXT:    [[C1:%.*]] = icmp ult i32 %x, -2147483647
-; CHECK-NEXT:    [[C2:%.*]] = icmp eq i32 %x, -1
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[X_OFF:%.*]] = add i32 %x, 2147483647
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt i32 [[X_OFF]], 2147483645
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp ult i32 %x, 2147483649
   %c2 = icmp eq i32 %x, 4294967295
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_7(i32 %x) {
 ; CHECK-LABEL: @PR42691_7(
 ; CHECK-NEXT:    [[TMP1:%.*]] = add i32 %x, -1
 ; CHECK-NEXT:    [[TMP2:%.*]] = icmp slt i32 [[TMP1]], 0
 ; CHECK-NEXT:    ret i1 [[TMP2]]
 ;
   %c1 = icmp uge i32 %x, 2147483649
   %c2 = icmp eq i32 %x, 0
   %c = or i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_8(i32 %x) {
 ; CHECK-LABEL: @PR42691_8(
-; CHECK-NEXT:    [[C1:%.*]] = icmp slt i32 %x, 14
-; CHECK-NEXT:    [[C2:%.*]] = icmp ne i32 %x, -2147483648
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[X_OFF:%.*]] = add i32 %x, 2147483647
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i32 [[X_OFF]], -2147483635
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp slt i32 %x, 14
   %c2 = icmp ne i32 %x, -2147483648
   %c = and i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_9(i32 %x) {
 ; CHECK-LABEL: @PR42691_9(
-; CHECK-NEXT:    [[C1:%.*]] = icmp sgt i32 %x, 13
-; CHECK-NEXT:    [[C2:%.*]] = icmp ne i32 %x, 2147483647
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[X_OFF:%.*]] = add i32 %x, -14
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i32 [[X_OFF]], 2147483633
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp sgt i32 %x, 13
   %c2 = icmp ne i32 %x, 2147483647
   %c = and i1 %c1, %c2
   ret i1 %c
 }
 
 define i1 @PR42691_10(i32 %x) {
 ; CHECK-LABEL: @PR42691_10(
-; CHECK-NEXT:    [[C1:%.*]] = icmp ugt i32 %x, 13
-; CHECK-NEXT:    [[C2:%.*]] = icmp ne i32 %x, -1
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    [[X_OFF:%.*]] = add i32 %x, -14
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i32 [[X_OFF]], -15
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %c1 = icmp ugt i32 %x, 13
   %c2 = icmp ne i32 %x, 4294967295
   %c = and i1 %c1, %c2
   ret i1 %c
 }