Add a really quick hack at a machine code sinking pass, enabled with --enable-sinking.
It is missing validity checks, so it is known broken. However, it is powerful enough
to compile this contrived code:
void test1(int C, double A, double B, double *P) {
double Tmp = A*A+B*B;
*P = C ? Tmp : A;
}
into:
_test1:
movsd 8(%esp), %xmm0
cmpl $0, 4(%esp)
je LBB1_2 # entry
LBB1_1: # entry
movsd 16(%esp), %xmm1
mulsd %xmm1, %xmm1
mulsd %xmm0, %xmm0
addsd %xmm1, %xmm0
LBB1_2: # entry
movl 24(%esp), %eax
movsd %xmm0, (%eax)
ret
instead of:
_test1:
movsd 16(%esp), %xmm0
mulsd %xmm0, %xmm0
movsd 8(%esp), %xmm1
movapd %xmm1, %xmm2
mulsd %xmm2, %xmm2
addsd %xmm0, %xmm2
cmpl $0, 4(%esp)
je LBB1_2 # entry
LBB1_1: # entry
movapd %xmm2, %xmm1
LBB1_2: # entry
movl 24(%esp), %eax
movsd %xmm1, (%eax)
ret
woo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45570 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index 0528434..6a8e775 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -29,6 +29,12 @@
static cl::opt<bool> PrintEmittedAsm("print-emitted-asm", cl::Hidden,
cl::desc("Dump emitter generated instructions as assembly"));
+// Hidden options to help debugging
+static cl::opt<bool>
+EnableSinking("enable-sinking", cl::init(false), cl::Hidden,
+ cl::desc("Perform sinking on machine code"));
+
+
FileModel::Model
LLVMTargetMachine::addPassesToEmitFile(FunctionPassManager &PM,
std::ostream &Out,
@@ -68,6 +74,9 @@
PM.add(createMachineFunctionPrinterPass(cerr));
PM.add(createMachineLICMPass());
+
+ if (EnableSinking)
+ PM.add(createMachineSinkingPass());
// Perform register allocation to convert to a concrete x86 representation
PM.add(createRegisterAllocator());