[llvm] 9a33f39 - [ConstraintElimination] Transfer info from SLT to unsigned system.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2022-06-23T15:57:59+02:00
New Revision: 9a33f3975e1a0cbfcfa3e5455b0d1429b98fabf4

URL: https://github.com/llvm/llvm-project/commit/9a33f3975e1a0cbfcfa3e5455b0d1429b98fabf4
DIFF: https://github.com/llvm/llvm-project/commit/9a33f3975e1a0cbfcfa3e5455b0d1429b98fabf4.diff

LOG: [ConstraintElimination] Transfer info from SLT to unsigned system.

If A s< B holds, then A u< also holds, if A s>= 0.

https://alive2.llvm.org/ce/z/J4JZuN

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
    llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 9d047640bffbc..6508744e28c04 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -403,6 +403,10 @@ void ConstraintInfo::transferToOtherSystem(
   switch (Pred) {
   default:
     break;
+  case CmpInst::ICMP_SLT:
+    if (doesHold(CmpInst::ICMP_SGE, A, ConstantInt::get(B->getType(), 0)))
+      addFact(CmpInst::ICMP_ULT, A, B, IsNegated, NumIn, NumOut, DFSInStack);
+    break;
   case CmpInst::ICMP_SGT:
     if (doesHold(CmpInst::ICMP_SGE, B, ConstantInt::get(B->getType(), -1)))
       addFact(CmpInst::ICMP_UGE, A, ConstantInt::get(B->getType(), 0),

diff  --git a/llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll b/llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll
index e953615a3e848..28f4aa8e5460b 100644
--- a/llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll
+++ b/llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll
@@ -13,7 +13,7 @@ define i1 @len_known_positive_via_idx_1(i8 %len, i8 %idx) {
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp sge i8 [[LEN]], 0
 ; CHECK-NEXT:    [[C_1:%.*]] = icmp sge i8 [[LEN]], 2
 ; CHECK-NEXT:    [[C_2:%.*]] = icmp sge i8 [[LEN]], 2
-; CHECK-NEXT:    [[RES_1:%.*]] = xor i1 [[T_1]], true
+; CHECK-NEXT:    [[RES_1:%.*]] = xor i1 true, true
 ; CHECK-NEXT:    [[RES_2:%.*]] = xor i1 [[RES_1]], [[C_1]]
 ; CHECK-NEXT:    [[RES_3:%.*]] = xor i1 [[RES_2]], [[C_2]]
 ; CHECK-NEXT:    ret i1 [[RES_3]]
@@ -609,7 +609,7 @@ define i1 @slt_first_op_known_pos(i8 %idx) {
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp ult i8 2, [[IDX]]
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp ult i8 1, [[IDX]]
-; CHECK-NEXT:    [[RES_1:%.*]] = xor i1 [[T_1]], [[T_2]]
+; CHECK-NEXT:    [[RES_1:%.*]] = xor i1 true, true
 ; CHECK-NEXT:    [[C_1:%.*]] = icmp ult i8 3, [[IDX]]
 ; CHECK-NEXT:    [[RES_2:%.*]] = xor i1 [[RES_1]], [[C_1]]
 ; CHECK-NEXT:    ret i1 [[RES_2]]