r340141 - [CodeGen] add rotate builtins that map to LLVM funnel shift
Sanjay Patel via cfe-commits
cfe-commits at lists.llvm.org
Sun Aug 19 09:50:30 PDT 2018
Author: spatel
Date: Sun Aug 19 09:50:30 2018
New Revision: 340141
URL: http://llvm.org/viewvc/llvm-project?rev=340141&view=rev
Log:
[CodeGen] add rotate builtins that map to LLVM funnel shift
This is a partial retry of rL340137 (reverted at rL340138 because of gcc host compiler crashing)
with 1 change:
Remove the changes to make microsoft builtins also use the LLVM intrinsics.
This exposes the LLVM funnel shift intrinsics as more familiar bit rotation functions in clang
(when both halves of a funnel shift are the same value, it's a rotate).
We're free to name these as we want because we're not copying gcc, but if there's some other
existing art (eg, the microsoft ops) that we want to replicate, we can change the names.
The funnel shift intrinsics were added here:
https://reviews.llvm.org/D49242
With improved codegen in:
https://reviews.llvm.org/rL337966
https://reviews.llvm.org/rL339359
And basic IR optimization added in:
https://reviews.llvm.org/rL338218
https://reviews.llvm.org/rL340022
...so these are expected to produce asm output that's equal or better to the multi-instruction
alternatives using primitive C/IR ops.
In the motivating loop example from PR37387:
https://bugs.llvm.org/show_bug.cgi?id=37387#c7
...we get the expected 'rolq' x86 instructions if we substitute the rotate builtin into the source.
Differential Revision: https://reviews.llvm.org/D50924
Modified:
cfe/trunk/docs/LanguageExtensions.rst
cfe/trunk/include/clang/Basic/Builtins.def
cfe/trunk/lib/CodeGen/CGBuiltin.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.h
Modified: cfe/trunk/docs/LanguageExtensions.rst
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/LanguageExtensions.rst?rev=340141&r1=340140&r2=340141&view=diff
==============================================================================
--- cfe/trunk/docs/LanguageExtensions.rst (original)
+++ cfe/trunk/docs/LanguageExtensions.rst Sun Aug 19 09:50:30 2018
@@ -1739,6 +1739,70 @@ The '``__builtin_bitreverse``' family of
the bitpattern of an integer value; for example ``0b10110110`` becomes
``0b01101101``.
+``__builtin_rotateleft``
+------------------------
+
+* ``__builtin_rotateleft8``
+* ``__builtin_rotateleft16``
+* ``__builtin_rotateleft32``
+* ``__builtin_rotateleft64``
+
+**Syntax**:
+
+.. code-block:: c++
+
+ __builtin_rotateleft32(x, y)
+
+**Examples**:
+
+.. code-block:: c++
+
+ uint8_t rot_x = __builtin_rotateleft8(x, y);
+ uint16_t rot_x = __builtin_rotateleft16(x, y);
+ uint32_t rot_x = __builtin_rotateleft32(x, y);
+ uint64_t rot_x = __builtin_rotateleft64(x, y);
+
+**Description**:
+
+The '``__builtin_rotateleft``' family of builtins is used to rotate
+the bits in the first argument by the amount in the second argument.
+For example, ``0b10000110`` rotated left by 11 becomes ``0b00110100``.
+The shift value is treated as an unsigned amount modulo the size of
+the arguments. Both arguments and the result have the bitwidth specified
+by the name of the builtin.
+
+``__builtin_rotateright``
+_------------------------
+
+* ``__builtin_rotateright8``
+* ``__builtin_rotateright16``
+* ``__builtin_rotateright32``
+* ``__builtin_rotateright64``
+
+**Syntax**:
+
+.. code-block:: c++
+
+ __builtin_rotateright32(x, y)
+
+**Examples**:
+
+.. code-block:: c++
+
+ uint8_t rot_x = __builtin_rotateright8(x, y);
+ uint16_t rot_x = __builtin_rotateright16(x, y);
+ uint32_t rot_x = __builtin_rotateright32(x, y);
+ uint64_t rot_x = __builtin_rotateright64(x, y);
+
+**Description**:
+
+The '``__builtin_rotateright``' family of builtins is used to rotate
+the bits in the first argument by the amount in the second argument.
+For example, ``0b10000110`` rotated right by 3 becomes ``0b11010000``.
+The shift value is treated as an unsigned amount modulo the size of
+the arguments. Both arguments and the result have the bitwidth specified
+by the name of the builtin.
+
``__builtin_unreachable``
-------------------------
Modified: cfe/trunk/include/clang/Basic/Builtins.def
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Builtins.def?rev=340141&r1=340140&r2=340141&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/Builtins.def (original)
+++ cfe/trunk/include/clang/Basic/Builtins.def Sun Aug 19 09:50:30 2018
@@ -428,6 +428,15 @@ BUILTIN(__builtin_bitreverse16, "UsUs",
BUILTIN(__builtin_bitreverse32, "UiUi", "nc")
BUILTIN(__builtin_bitreverse64, "ULLiULLi", "nc")
+BUILTIN(__builtin_rotateleft8, "UcUcUc", "nc")
+BUILTIN(__builtin_rotateleft16, "UsUsUs", "nc")
+BUILTIN(__builtin_rotateleft32, "UiUiUi", "nc")
+BUILTIN(__builtin_rotateleft64, "ULLiULLiULLi", "nc")
+BUILTIN(__builtin_rotateright8, "UcUcUc", "nc")
+BUILTIN(__builtin_rotateright16, "UsUsUs", "nc")
+BUILTIN(__builtin_rotateright32, "UiUiUi", "nc")
+BUILTIN(__builtin_rotateright64, "ULLiULLiULLi", "nc")
+
// Random GCC builtins
BUILTIN(__builtin_constant_p, "i.", "nctu")
BUILTIN(__builtin_classify_type, "i.", "nctu")
Modified: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBuiltin.cpp?rev=340141&r1=340140&r2=340141&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBuiltin.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp Sun Aug 19 09:50:30 2018
@@ -1252,6 +1252,21 @@ static llvm::Value *dumpRecord(CodeGenFu
return Res;
}
+RValue CodeGenFunction::emitRotate(const CallExpr *E, bool IsRotateRight) {
+ llvm::Value *Src = EmitScalarExpr(E->getArg(0));
+ llvm::Value *ShiftAmt = EmitScalarExpr(E->getArg(1));
+
+ // The builtin's shift arg may have a different type than the source arg and
+ // result, but the LLVM intrinsic uses the same type for all values.
+ llvm::Type *Ty = Src->getType();
+ ShiftAmt = Builder.CreateIntCast(ShiftAmt, Ty, false);
+
+ // Rotate is a special case of LLVM funnel shift - 1st 2 args are the same.
+ unsigned IID = IsRotateRight ? Intrinsic::fshr : Intrinsic::fshl;
+ Value *F = CGM.getIntrinsic(IID, Ty);
+ return RValue::get(Builder.CreateCall(F, { Src, Src, ShiftAmt }));
+}
+
RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
unsigned BuiltinID, const CallExpr *E,
ReturnValueSlot ReturnValue) {
@@ -1741,6 +1756,18 @@ RValue CodeGenFunction::EmitBuiltinExpr(
case Builtin::BI__builtin_bitreverse64: {
return RValue::get(emitUnaryBuiltin(*this, E, Intrinsic::bitreverse));
}
+ case Builtin::BI__builtin_rotateleft8:
+ case Builtin::BI__builtin_rotateleft16:
+ case Builtin::BI__builtin_rotateleft32:
+ case Builtin::BI__builtin_rotateleft64:
+ return emitRotate(E, false);
+
+ case Builtin::BI__builtin_rotateright8:
+ case Builtin::BI__builtin_rotateright16:
+ case Builtin::BI__builtin_rotateright32:
+ case Builtin::BI__builtin_rotateright64:
+ return emitRotate(E, true);
+
case Builtin::BI__builtin_object_size: {
unsigned Type =
E->getArg(1)->EvaluateKnownConstInt(getContext()).getZExtValue();
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=340141&r1=340140&r2=340141&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Sun Aug 19 09:50:30 2018
@@ -3681,6 +3681,8 @@ public:
unsigned BuiltinID, const CallExpr *E,
ReturnValueSlot ReturnValue);
+ RValue emitRotate(const CallExpr *E, bool IsRotateRight);
+
/// Emit IR for __builtin_os_log_format.
RValue emitBuiltinOSLogFormat(const CallExpr &E);
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