Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp =================================================================== --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -4455,6 +4455,14 @@ return DAG.getNode(ISD::ADD, SDLoc(N), VT, Shl0, Shl1); } + // fold (shl (mul x, c1), c2) -> (mul x, c1 << c2) + if (N1C && N0.getOpcode() == ISD::MUL && N0.getNode()->hasOneUse()) { + if (ConstantSDNode *N0C1 = isConstOrConstSplat(N0.getOperand(1))) { + SDValue Folded = DAG.FoldConstantArithmetic(ISD::SHL, SDLoc(N1), VT, N0C1, N1C); + return DAG.getNode(ISD::MUL, SDLoc(N), VT, N0.getOperand(0), Folded); + } + } + if (N1C && !N1C->isOpaque()) if (SDValue NewSHL = visitShiftByConstant(N, N1C)) return NewSHL; Index: test/CodeGen/ARM/gep-optimization.ll =================================================================== --- /dev/null +++ test/CodeGen/ARM/gep-optimization.ll @@ -0,0 +1,77 @@ +; RUN: llc < %s -mtriple=armv7a-eabi | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-AT2 +; RUN: llc < %s -mtriple=thumbv7m-eabi | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-AT2 +; RUN: llc < %s -mtriple=thumbv6m-eabi | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-T1 + +; This test checks that various kinds of getelementptr are all optimised to a +; simple multiply plus add, with the add being done by a register offset if the +; result is used in a load. + +; CHECK-LABEL: calc_1d: +; CHECK: mov{{s?}} [[REG1:r[0-9]+]], #84 +; CHECK-AT2: mla r0, r1, [[REG1]], r0 +; CHECK-T1: muls [[REG2:r[0-9]+]], r1, [[REG1]] +; CHECK-T1: adds r0, r0, [[REG2]] +define i32* @calc_1d(i32* %p, i32 %n) { +entry: + %mul = mul nsw i32 %n, 21 + %add.ptr = getelementptr inbounds i32, i32* %p, i32 %mul + ret i32* %add.ptr +} + +; CHECK-LABEL: load_1d: +; CHECK: mov{{s?}} [[REG1:r[0-9]+]], #84 +; CHECK: mul{{s?}} [[REG2:r[0-9]+]],{{( r1,)?}} [[REG1]]{{(, r1)?}} +; CHECK: ldr r0, [r0, [[REG2]]] +define i32 @load_1d(i32* %p, i32 %n) #1 { +entry: + %mul = mul nsw i32 %n, 21 + %arrayidx = getelementptr inbounds i32, i32* %p, i32 %mul + %0 = load i32, i32* %arrayidx, align 4 + ret i32 %0 +} + +; CHECK-LABEL: calc_2d_a: +; CHECK: mov{{s?}} [[REG1:r[0-9]+]], #84 +; CHECK-AT2: mla r0, r1, [[REG1]], r0 +; CHECK-T1: muls [[REG2:r[0-9]+]], r1, [[REG1]] +; CHECK-T1: adds r0, r0, [[REG2]] +define i32* @calc_2d_a([100 x i32]* %p, i32 %n) { +entry: + %mul = mul nsw i32 %n, 21 + %arrayidx1 = getelementptr inbounds [100 x i32], [100 x i32]* %p, i32 0, i32 %mul + ret i32* %arrayidx1 +} + +; CHECK-LABEL: load_2d_a: +; CHECK: mov{{s?}} [[REG1:r[0-9]+]], #84 +; CHECK: mul{{s?}} [[REG2:r[0-9]+]],{{( r1,)?}} [[REG1]]{{(, r1)?}} +; CHECK: ldr r0, [r0, [[REG2]]] +define i32 @load_2d_a([100 x i32]* %p, i32 %n) #1 { +entry: + %mul = mul nsw i32 %n, 21 + %arrayidx1 = getelementptr inbounds [100 x i32], [100 x i32]* %p, i32 0, i32 %mul + %0 = load i32, i32* %arrayidx1, align 4 + ret i32 %0 +} + +; CHECK-LABEL: calc_2d_b: +; CHECK: mov{{s?}} [[REG1:r[0-9]+]], #84 +; CHECK-AT2: mla r0, r1, [[REG1]], r0 +; CHECK-T1: muls [[REG2:r[0-9]+]], r1, [[REG1]] +; CHECK-T1: adds r0, r0, [[REG2]] +define i32* @calc_2d_b([21 x i32]* %p, i32 %n) { +entry: + %arrayidx1 = getelementptr inbounds [21 x i32], [21 x i32]* %p, i32 %n, i32 0 + ret i32* %arrayidx1 +} + +; CHECK-LABEL: load_2d_b: +; CHECK: mov{{s?}} [[REG1:r[0-9]+]], #84 +; CHECK: mul{{s?}} [[REG2:r[0-9]+]],{{( r1,)?}} [[REG1]]{{(, r1)?}} +; CHECK: ldr r0, [r0, [[REG2]]] +define i32 @load_2d_b([21 x i32]* %p, i32 %n) { +entry: + %arrayidx1 = getelementptr inbounds [21 x i32], [21 x i32]* %p, i32 %n, i32 0 + %0 = load i32, i32* %arrayidx1, align 4 + ret i32 %0 +}