[llvm] 24a9888 - [ConstraintElimination] Transfer info from SGT to unsigned system.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2022-06-23T11:04:51+02:00
New Revision: 24a98881cdb458376fc23ace6247b62084b4ad38

URL: https://github.com/llvm/llvm-project/commit/24a98881cdb458376fc23ace6247b62084b4ad38
DIFF: https://github.com/llvm/llvm-project/commit/24a98881cdb458376fc23ace6247b62084b4ad38.diff

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

If A >s B then A >=u 0, if B >=s -1.

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

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index f3bbc77084778..9d047640bffbc 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -403,6 +403,11 @@ void ConstraintInfo::transferToOtherSystem(
   switch (Pred) {
   default:
     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),
+              IsNegated, NumIn, NumOut, DFSInStack);
+    break;
   case CmpInst::ICMP_SGE:
     if (doesHold(CmpInst::ICMP_SGE, B, ConstantInt::get(B->getType(), 0))) {
       addFact(CmpInst::ICMP_UGE, A, B, IsNegated, NumIn, NumOut, DFSInStack);

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 0eb95323a4d61..e953615a3e848 100644
--- a/llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll
+++ b/llvm/test/Transforms/ConstraintElimination/transfer-signed-facts-to-unsigned.ll
@@ -164,7 +164,7 @@ define i1 @cnt_positive_sgt_against_base(ptr %p, i32 %cnt) {
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    [[ADD_PTR:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i32 [[CNT]]
 ; CHECK-NEXT:    [[CMP_1:%.*]] = icmp uge ptr [[ADD_PTR]], [[P]]
-; CHECK-NEXT:    br i1 [[CMP_1]], label [[THEN:%.*]], label [[ELSE:%.*]]
+; CHECK-NEXT:    br i1 true, label [[THEN:%.*]], label [[ELSE:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    ret i1 false
 ; CHECK:       else:
@@ -246,7 +246,7 @@ define i1 @cnt_positive_sgt_against_base_with_zext(ptr %p, i32 %cnt) {
 ; CHECK-NEXT:    [[EXT:%.*]] = zext i32 [[CNT]] to i64
 ; CHECK-NEXT:    [[ADD_PTR:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[EXT]]
 ; CHECK-NEXT:    [[CMP_1:%.*]] = icmp uge ptr [[ADD_PTR]], [[P]]
-; CHECK-NEXT:    br i1 [[CMP_1]], label [[THEN:%.*]], label [[ELSE:%.*]]
+; CHECK-NEXT:    br i1 true, label [[THEN:%.*]], label [[ELSE:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    ret i1 false
 ; CHECK:       else:
@@ -563,7 +563,7 @@ define i1 @sgt_known_neg(i8 %idx) {
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp uge i8 [[IDX]], 0
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp uge i8 [[IDX]], 1
-; CHECK-NEXT:    [[RES_1:%.*]] = xor i1 [[T_1]], [[T_2]]
+; CHECK-NEXT:    [[RES_1:%.*]] = xor i1 true, [[T_2]]
 ; CHECK-NEXT:    [[C_1:%.*]] = icmp ugt i8 [[IDX]], -1
 ; CHECK-NEXT:    [[RES_2:%.*]] = xor i1 [[RES_1]], [[C_1]]
 ; CHECK-NEXT:    ret i1 [[RES_2]]