From 432ca7460b008060245c92e1a4c3ff4cf787e0ce Mon Sep 17 00:00:00 2001 From: Weiming Zhao Date: Fri, 8 Jan 2016 18:43:41 +0000 Subject: [PATCH] RBIT Instruction only available for ARMv6t2 and above. Summary: r255334 matches bit-reverse pattern in InstCombine and generates calls to Instrinsic::bitreverse. RBIT instruction is only available for ARMv6t2 and above. This patch has the intrinsic expanded during legalization for ARMv4 and ARMv5. Patch by Z. Zheng Reviewers: apazos, jmolloy, weimingz Subscribers: aemerson, rengolin, llvm-commits Differential Revision: http://reviews.llvm.org/D15932 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257188 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/ARM/ARMISelLowering.cpp | 2 +- test/CodeGen/ARM/bit-reverse-to-rbit.ll | 34 +++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 1 deletion(-) create mode 100644 test/CodeGen/ARM/bit-reverse-to-rbit.ll diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp index fc57d83ce1e..1f93d2c38b9 100644 --- a/lib/Target/ARM/ARMISelLowering.cpp +++ b/lib/Target/ARM/ARMISelLowering.cpp @@ -744,7 +744,7 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM, setOperationAction(ISD::SUBE, MVT::i32, Custom); } - if (!Subtarget->isThumb1Only()) + if (!Subtarget->isThumb1Only() && Subtarget->hasV6T2Ops()) setOperationAction(ISD::BITREVERSE, MVT::i32, Legal); // ARM does not have ROTL. diff --git a/test/CodeGen/ARM/bit-reverse-to-rbit.ll b/test/CodeGen/ARM/bit-reverse-to-rbit.ll new file mode 100644 index 00000000000..8482cbf69f2 --- /dev/null +++ b/test/CodeGen/ARM/bit-reverse-to-rbit.ll @@ -0,0 +1,34 @@ +;RUN: opt -instcombine -S < %s | llc -mtriple=armv5e--linux-gnueabi | FileCheck %s +;RUN: opt -instcombine -S < %s | llc -mtriple=thumbv4t--linux-gnueabi | FileCheck %s +;RUN: opt -instcombine -S < %s | llc -mtriple=armv6--linux-gnueabi | FileCheck %s + +;RUN: opt -instcombine -S < %s | llc -mtriple=armv7--linux-gnueabi | FileCheck %s --check-prefix=RBIT +;RUN: opt -instcombine -S < %s | llc -mtriple=thumbv8--linux-gnueabi | FileCheck %s --check-prefix=RBIT + +;CHECK-NOT: rbit +;RBIT: rbit + +define void @byte_reversal(i8* %p, i32 %n) { +entry: + br label %for.cond + +for.cond: ; preds = %for.body, %entry + %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ] + %cmp = icmp ult i32 %i.0, %n + br i1 %cmp, label %for.body, label %for.end + +for.body: ; preds = %for.cond + %0 = sext i32 %i.0 to i64 + %arrayidx = getelementptr inbounds i8, i8* %p, i64 %0 + %1 = load i8, i8* %arrayidx, align 1 + %or19 = call i8 @llvm.bitreverse.i8(i8 %1) + store i8 %or19, i8* %arrayidx, align 1 + %inc = add i32 %i.0, 1 + br label %for.cond + +for.end: ; preds = %for.cond + ret void +} + +; Function Attrs: nounwind readnone +declare i8 @llvm.bitreverse.i8(i8) -- 2.11.0