[coreboot-gerrit] [S] Change in coreboot[master]: lib/lzmadecode: Allow for 8 byte reads on 64bit

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/70175 )

Change subject: lib/lzmadecode: Allow for 8 byte reads on 64bit
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lib/lzmadecode: Allow for 8 byte reads on 64bit

This adds an optimization to lzma decode to also read from the boot
medium in chunks of 8 bytes if that is the general purpose register
length instead of always 4 bytes. It depends on the cache / memory / spi
controller whether this is faster, but it's likely to be either the same
or faster.

TESTED
- google/vilboz: cached boot medium
64bit before - 32bit - 64bit after
load FSP-M: 35,674 - 35,595 - 34,690
load ramstage: 42,134 - 43,378 - 40,882
load FSP-S: 24,954 - 25,496 - 24,368

- foxconn/g41m: uncached boot medium for testing
64bit before - 32bit - 64bit after
load ramstage: 51,164 - 51,872 - 64,892

Change-Id: I890c075307c0aec877618d9902ea352ae42a3bfa
Signed-off-by: Arthur Heymans 
---
M src/lib/lzmadecode.c
M src/lib/lzmadecode.h
2 files changed, 37 insertions(+), 10 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/75/70175/1

diff --git a/src/lib/lzmadecode.c b/src/lib/lzmadecode.c
index cb86829..5c6baa4 100644
--- a/src/lib/lzmadecode.c
+++ b/src/lib/lzmadecode.c
@@ -35,15 +35,15 @@
 #define kBitModelTotal (1 << kNumBitModelTotalBits)
 #define kNumMoveBits 5

-/* Use 32-bit reads whenever possible to avoid bad flash performance. Fall back
- * to byte reads for last 4 bytes since RC_TEST returns an error when BufferLim
+/* Use sizeof(SizeT) sized reads whenever possible to avoid bad flash performance. Fall back
+ * to byte reads for last sizeof(SizeT) bytes since RC_TEST returns an error when BufferLim
  * is *reached* (not surpassed!), meaning we can't allow that to happen while
  * there are still bytes to decode from the algorithm's point of view. */
 #define RC_READ_BYTE							\
-	(look_ahead_ptr < 4 ? look_ahead.raw[look_ahead_ptr++]		\
-	: ((((uintptr_t) Buffer & 3)					\
-		|| ((SizeT) (BufferLim - Buffer) <= 4)) ? (*Buffer++)	\
-	: ((look_ahead.dw = *(UInt32 *)Buffer), (Buffer += 4),		\
+	(look_ahead_ptr < sizeof(SizeT) ? look_ahead.raw[look_ahead_ptr++]	\
+	 : ((((uintptr_t) Buffer & (sizeof(SizeT) - 1))				\
+	     || ((SizeT) (BufferLim - Buffer) <= sizeof(SizeT))) ? (*Buffer++) \
+	   : ((look_ahead.dw = *(SizeT *)Buffer), (Buffer += sizeof(SizeT)),	\
    	(look_ahead_ptr = 1), look_ahead.raw[0])))

#define RC_INIT2 Code = 0; Range = 0xFFFFFFFF;		\
@@ -207,10 +207,10 @@
    int len = 0;
    const Byte *Buffer;
    const Byte *BufferLim;
-	int look_ahead_ptr = 4;
+	int look_ahead_ptr = sizeof(SizeT);
    union {
-		Byte raw[4];
-		UInt32 dw;
+		Byte raw[sizeof(SizeT)];
+		SizeT dw;
    } look_ahead;
    UInt32 Range;
    UInt32 Code;
diff --git a/src/lib/lzmadecode.h b/src/lib/lzmadecode.h
index 9ed352a..d897af7 100644
--- a/src/lib/lzmadecode.h
+++ b/src/lib/lzmadecode.h
@@ -25,7 +25,7 @@
 typedef unsigned char Byte;
 typedef unsigned short UInt16;
 typedef unsigned int UInt32;
-typedef UInt32 SizeT;
+typedef unsigned long int SizeT;

#define CProb UInt16