runtime: use unsigned load for iscgo variable in ppc64x runtime asm

This changes the runtime asm code that loads iscgo to use MOVBZ
instead of MOVB, avoiding an unnecessary sign extension. This is most
significant in runtime.save_g, reducing the size from 8 to 7
instructions.

Change-Id: Iaa2121464b5309e1f27fd91b19b5603c7aaf619d
Reviewed-on: https://go-review.googlesource.com/c/144217
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index e77c7179354927903875f4646e6d45011c88e987..87076817f977f9661b8fb9687ea8804cf68b19f1 100644 (file)
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -648,7 +648,7 @@ TEXT ·cgocallback_gofunc(SB),NOSPLIT,$16-32
        NO_LOCAL_POINTERS
 
        // Load m and g from thread-local storage.
-       MOVB    runtime·iscgo(SB), R3
+       MOVBZ   runtime·iscgo(SB), R3
        CMP     R3, $0
        BEQ     nocgo
        BL      runtime·load_g(SB)

diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index 5b5df50d41ba7790ea047debc0cb343c3ed036f9..bf01099830799c0a8fe8989a51c95d1e3dfd9571 100644 (file)
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -301,7 +301,7 @@ TEXT runtime·_sigtramp(SB),NOSPLIT,$64
 
        // this might be called in external code context,
        // where g is not set.
-       MOVB    runtime·iscgo(SB), R6
+       MOVBZ   runtime·iscgo(SB), R6
        CMP     R6, $0
        BEQ     2(PC)
        BL      runtime·load_g(SB)

diff --git a/src/runtime/tls_ppc64x.s b/src/runtime/tls_ppc64x.s
index 82714853ee7a84f2794dbe0cdf575dcfcf9f2f4e..c6974492828ea64f0f3f5bf3e28af07305cf5c45 100644 (file)
--- a/src/runtime/tls_ppc64x.s
+++ b/src/runtime/tls_ppc64x.s
@@ -24,7 +24,7 @@
 // NOTE: setg_gcc<> assume this clobbers only R31.
 TEXT runtime·save_g(SB),NOSPLIT|NOFRAME,$0-0
 #ifndef GOOS_aix
-       MOVB    runtime·iscgo(SB), R31
+       MOVBZ   runtime·iscgo(SB), R31
        CMP     R31, $0
        BEQ     nocgo
 #endif