Roll SwiftShader from 82d425db023c to 39fdd0d506bf (6 revisions)

https://swiftshader.googlesource.com/SwiftShader.git/+log/82d425db023c..39fdd0d506bf

2022-03-03 capn@google.com Benchmark mediump GLSL.std.450 instructions
2022-03-03 capn@google.com Simplify obtaining SPIR-V decorations
2022-03-03 capn@google.com Remove duplicate transcendental functions
2022-03-03 capn@google.com Optimize log2() polynomial evaluation using FMA
2022-03-03 capn@google.com Remove exp/log constant propagation TODOs
2022-03-03 capn@google.com Optimize exp2() polynomial evaluation using FMA

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/swiftshader-dawn-autoroll
Please CC bclayton@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in SwiftShader: https://bugs.chromium.org/p/swiftshader/issues/entry
To file a bug in Dawn: https://bugs.chromium.org/p/dawn/issues/entry

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Bug: None
Tbr: bclayton@google.com
Change-Id: Ibfe34e0461f6956d8c16e1232511199eccb3c391
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/82620
Bot-Commit: Dawn Autoroller <dawn-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: Dawn Autoroller <dawn-autoroll@skia-public.iam.gserviceaccount.com>

DEPS

@@ -133,7 +133,7 @@ deps = {
   },
 
   'third_party/swiftshader': {
-    'url': '{swiftshader_git}/SwiftShader@82d425db023c0d89d27365cb24987f3a47a5b86a',
+    'url': '{swiftshader_git}/SwiftShader@39fdd0d506bfc673068c27e9ad4ee975fbbd38ed',
     'condition': 'dawn_standalone',
   },