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Re: Correct PowerPC64 local-dynamic TLS linker optimization
- From: Alan Modra <amodra at gmail dot com>
- To: binutils at sourceware dot org
- Date: Thu, 29 Jan 2015 20:37:07 +1030
- Subject: Re: Correct PowerPC64 local-dynamic TLS linker optimization
- Authentication-results: sourceware.org; auth=none
- References: <20150129024617 dot GC12931 at bubble dot grove dot modra dot org>
On Thu, Jan 29, 2015 at 01:16:18PM +1030, Alan Modra wrote:
> The linker hardcoded r3 into a local-dynamic to local-exec TLS
> optimization sequence. This is normally the case since r3 is required
> as a parameter to (the optimized out) __tls_get_addr call. However,
> it is possible for a compiler, LLVM in this case, to set up the
> parameter value in another register then copy it to r3 before the
> call.
And for gold.
* powerpc.cc (Target_powerpc::Relocate::relocate): Correct GOT_TLSLD
and GOT_TLSGD to LE optimization.
diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index 2eae938..ac8d05b 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -3178,8 +3178,6 @@ static const uint32_t addi_11_11 = 0x396b0000;
static const uint32_t addi_12_12 = 0x398c0000;
static const uint32_t addis_0_2 = 0x3c020000;
static const uint32_t addis_0_13 = 0x3c0d0000;
-static const uint32_t addis_3_2 = 0x3c620000;
-static const uint32_t addis_3_13 = 0x3c6d0000;
static const uint32_t addis_11_2 = 0x3d620000;
static const uint32_t addis_11_11 = 0x3d6b0000;
static const uint32_t addis_11_30 = 0x3d7e0000;
@@ -7008,9 +7006,12 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
|| r_type == elfcpp::R_POWERPC_GOT_TLSGD16_LO)
{
Insn* iview = reinterpret_cast<Insn*>(view - 2 * big_endian);
- Insn insn = addis_3_13;
+ Insn insn = elfcpp::Swap<32, big_endian>::readval(iview);
+ insn &= (1 << 26) - (1 << 21); // extract rt
if (size == 32)
- insn = addis_3_2;
+ insn |= addis_0_2;
+ else
+ insn |= addis_0_13;
elfcpp::Swap<32, big_endian>::writeval(iview, insn);
r_type = elfcpp::R_POWERPC_TPREL16_HA;
value = psymval->value(object, rela.get_r_addend());
@@ -7043,9 +7044,12 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
|| r_type == elfcpp::R_POWERPC_GOT_TLSLD16_LO)
{
Insn* iview = reinterpret_cast<Insn*>(view - 2 * big_endian);
- Insn insn = addis_3_13;
+ Insn insn = elfcpp::Swap<32, big_endian>::readval(iview);
+ insn &= (1 << 26) - (1 << 21); // extract rt
if (size == 32)
- insn = addis_3_2;
+ insn |= addis_0_2;
+ else
+ insn |= addis_0_13;
elfcpp::Swap<32, big_endian>::writeval(iview, insn);
r_type = elfcpp::R_POWERPC_TPREL16_HA;
value = dtp_offset;
--
Alan Modra
Australia Development Lab, IBM