[llvm-branch-commits] [llvm] efa9728 - [ConstraintElimination] Decompose GEP %ptr, SHL().

[Florian Hahn via llvm-branch-commits]

Author: Florian Hahn
Date: 2020-12-01T10:58:36Z
New Revision: efa9728a50012c9ead2b0110620e8865b36bef73

URL: https://github.com/llvm/llvm-project/commit/efa9728a50012c9ead2b0110620e8865b36bef73
DIFF: https://github.com/llvm/llvm-project/commit/efa9728a50012c9ead2b0110620e8865b36bef73.diff

LOG: [ConstraintElimination] Decompose GEP %ptr, SHL().

Add support the decompose a GEP with an SHL operand.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
    llvm/test/Transforms/ConstraintElimination/geps.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 608ef5337842..5c806b6e5486 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -57,6 +57,14 @@ static SmallVector<std::pair<int64_t, Value *>, 4> decompose(Value *V) {
                nullptr},
               {1, GEP->getPointerOperand()}};
     }
+    Value *Op0;
+    ConstantInt *CI;
+    if (match(GEP->getOperand(GEP->getNumOperands() - 1),
+              m_NUWShl(m_Value(Op0), m_ConstantInt(CI))))
+      return {{0, nullptr},
+              {1, GEP->getPointerOperand()},
+              {pow(2, CI->getSExtValue()), Op0}};
+
     return {{0, nullptr},
             {1, GEP->getPointerOperand()},
             {1, GEP->getOperand(GEP->getNumOperands() - 1)}};

diff  --git a/llvm/test/Transforms/ConstraintElimination/geps.ll b/llvm/test/Transforms/ConstraintElimination/geps.ll
index ed013ed2c961..52aea974294b 100644
--- a/llvm/test/Transforms/ConstraintElimination/geps.ll
+++ b/llvm/test/Transforms/ConstraintElimination/geps.ll
@@ -387,7 +387,7 @@ define void @test.ult.gep.shl(i32* readonly %src, i32* readnone %max, i32 %idx,
 ; CHECK-NEXT:    [[IDX_SHL_1:%.*]] = shl nuw i32 [[IDX]], 1
 ; CHECK-NEXT:    [[ADD_PTR_SHL_1:%.*]] = getelementptr inbounds i32, i32* [[SRC]], i32 [[IDX_SHL_1]]
 ; CHECK-NEXT:    [[C_MAX_0:%.*]] = icmp ult i32* [[ADD_PTR_SHL_1]], [[MAX]]
-; CHECK-NEXT:    call void @use(i1 [[C_MAX_0]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[IDX_SHL_2:%.*]] = shl nuw i32 [[IDX]], 2
 ; CHECK-NEXT:    [[ADD_PTR_SHL_2:%.*]] = getelementptr inbounds i32, i32* [[SRC]], i32 [[IDX_SHL_2]]
 ; CHECK-NEXT:    [[C_MAX_1:%.*]] = icmp ult i32* [[ADD_PTR_SHL_2]], [[MAX]]