diff options
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 11 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/implies.ll | 11 |
2 files changed, 22 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index d50140c3b9b..9ba33f49d8f 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -2179,6 +2179,17 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, if (isImpliedCondition(RHS, LHS)) return getTrue(ITy); break; + case ICmpInst::ICMP_SGE: + /// For signed comparison, the values for an i1 are 0 and -1 + /// respectively. This maps into a truth table of: + /// LHS | RHS | LHS >=s RHS | LHS implies RHS + /// 0 | 0 | 1 (0 >= 0) | 1 + /// 0 | 1 | 1 (0 >= -1) | 1 + /// 1 | 0 | 0 (-1 >= 0) | 0 + /// 1 | 1 | 1 (-1 >= -1) | 1 + if (isImpliedCondition(LHS, RHS)) + return getTrue(ITy); + break; case ICmpInst::ICMP_SLT: // X <s 0 -> X if (match(RHS, m_Zero())) diff --git a/llvm/test/Transforms/InstSimplify/implies.ll b/llvm/test/Transforms/InstSimplify/implies.ll index 80b6ac810d0..ac46b8d2828 100644 --- a/llvm/test/Transforms/InstSimplify/implies.ll +++ b/llvm/test/Transforms/InstSimplify/implies.ll @@ -91,3 +91,14 @@ define <4 x i1> @test6(<4 x i1> %a, <4 x i1> %b) { %res = icmp ule <4 x i1> %a, %b ret <4 x i1> %res } + +; X >=(s) Y == X ==> Y (i1 1 becomes -1 for reasoning) +define i1 @test_sge(i32 %length.i, i32 %i) { +; CHECK-LABEL: @test_sge +; CHECK: ret i1 true + %iplus1 = add nsw nuw i32 %i, 1 + %var29 = icmp ult i32 %i, %length.i + %var30 = icmp ult i32 %iplus1, %length.i + %res = icmp sge i1 %var30, %var29 + ret i1 %res +} |
