[PATCH] atheros/atlx: Simplify bit manipulations

From: Rasmus Villemoes
Date: Fri Jan 23 2015 - 06:07:51 EST


The code 'if (foo & X) foo &= ~X;' is semantically equivalent to
simply 'foo &= ~X;', but gcc generates about four instructions for the
former, one for the latter. Similarly, if X consists of a single bit,
'if (!(foo & X)) X |= X;' can be replaced by 'foo |= X;'.

In the atl2 case, gcc does know how to merge the new adjacent
operations, so altogether this gives a nice little code size
reduction of about 80 bytes.

Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/atheros/atlx/atl1.c | 3 +--
drivers/net/ethernet/atheros/atlx/atl2.c | 12 ++++--------
2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/atheros/atlx/atl1.c b/drivers/net/ethernet/atheros/atlx/atl1.c
index 2c8f398aeda9..d9d61d6e8386 100644
--- a/drivers/net/ethernet/atheros/atlx/atl1.c
+++ b/drivers/net/ethernet/atheros/atlx/atl1.c
@@ -1667,8 +1667,7 @@ static void atl1_via_workaround(struct atl1_adapter *adapter)
unsigned long value;

value = ioread16(adapter->hw.hw_addr + PCI_COMMAND);
- if (value & PCI_COMMAND_INTX_DISABLE)
- value &= ~PCI_COMMAND_INTX_DISABLE;
+ value &= ~PCI_COMMAND_INTX_DISABLE;
iowrite32(value, adapter->hw.hw_addr + PCI_COMMAND);
}

diff --git a/drivers/net/ethernet/atheros/atlx/atl2.c b/drivers/net/ethernet/atheros/atlx/atl2.c
index 84a09e8ddd9c..46d1b959daa8 100644
--- a/drivers/net/ethernet/atheros/atlx/atl2.c
+++ b/drivers/net/ethernet/atheros/atlx/atl2.c
@@ -1278,14 +1278,10 @@ static void atl2_setup_pcicmd(struct pci_dev *pdev)

pci_read_config_word(pdev, PCI_COMMAND, &cmd);

- if (cmd & PCI_COMMAND_INTX_DISABLE)
- cmd &= ~PCI_COMMAND_INTX_DISABLE;
- if (cmd & PCI_COMMAND_IO)
- cmd &= ~PCI_COMMAND_IO;
- if (0 == (cmd & PCI_COMMAND_MEMORY))
- cmd |= PCI_COMMAND_MEMORY;
- if (0 == (cmd & PCI_COMMAND_MASTER))
- cmd |= PCI_COMMAND_MASTER;
+ cmd &= ~PCI_COMMAND_INTX_DISABLE;
+ cmd &= ~PCI_COMMAND_IO;
+ cmd |= PCI_COMMAND_MEMORY;
+ cmd |= PCI_COMMAND_MASTER;
pci_write_config_word(pdev, PCI_COMMAND, cmd);

/*
--
2.1.3

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