Update llvm to trunk r256633.

1 files changed, 17 insertions, 10 deletions

diff --git a/contrib/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp b/contrib/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp
index 4434d9b..60e8c8f 100644
--- a/contrib/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp
+++ b/contrib/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp
@@ -99,14 +99,22 @@ void AMDGPUAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
 
     case AMDGPU::fixup_si_rodata: {
       uint32_t *Dst = (uint32_t*)(Data + Fixup.getOffset());
-      *Dst = Value;
-      break;
-    }
-
-    case AMDGPU::fixup_si_end_of_text: {
-      uint32_t *Dst = (uint32_t*)(Data + Fixup.getOffset());
-      // The value points to the last instruction in the text section, so we
-      // need to add 4 bytes to get to the start of the constants.
+      // We emit constant data at the end of the text section and generate its
+      // address using the following code sequence:
+      // s_getpc_b64 s[0:1]
+      // s_add_u32 s0, s0, $symbol
+      // s_addc_u32 s1, s1, 0
+      //
+      // s_getpc_b64 returns the address of the s_add_u32 instruction and then
+      // the fixup replaces $symbol with a literal constant, which is a
+      // pc-relative  offset from the encoding of the $symbol operand to the
+      // constant data.
+      //
+      // What we want here is an offset from the start of the s_add_u32
+      // instruction to the constant data, but since the encoding of $symbol
+      // starts 4 bytes after the start of the add instruction, we end up
+      // with an offset that is 4 bytes too small.  This requires us to
+      // add 4 to the fixup value before applying it.
       *Dst = Value + 4;
       break;
     }
@@ -136,8 +144,7 @@ const MCFixupKindInfo &AMDGPUAsmBackend::getFixupKindInfo(
   const static MCFixupKindInfo Infos[AMDGPU::NumTargetFixupKinds] = {
     // name                   offset bits  flags
     { "fixup_si_sopp_br",     0,     16,   MCFixupKindInfo::FKF_IsPCRel },
-    { "fixup_si_rodata",      0,     32,   0 },
-    { "fixup_si_end_of_text", 0,     32,   MCFixupKindInfo::FKF_IsPCRel }
+    { "fixup_si_rodata",      0,     32,   MCFixupKindInfo::FKF_IsPCRel }
   };
 
   if (Kind < FirstTargetFixupKind)