[AMDGPU] Add wave barrier builtin
The wave barrier represents the discardable barrier. Its main purpose is to
carry convergent attribute, thus preventing illegal CFG optimizations. All lanes
in a wave come to convergence point simultaneously with SIMT, thus no special
instruction is needed in the ISA. The barrier is discarded during code generation.
Differential Revision: https://reviews.llvm.org/D26585
llvm-svn: 287007
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUMCInstLower.cpp b/llvm/lib/Target/AMDGPU/AMDGPUMCInstLower.cpp
index cb259a3..7d56355 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUMCInstLower.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUMCInstLower.cpp
@@ -196,6 +196,12 @@
return;
}
+ if (MI->getOpcode() == AMDGPU::WAVE_BARRIER) {
+ if (isVerbose())
+ OutStreamer->emitRawComment(" wave barrier");
+ return;
+ }
+
MCInst TmpInst;
MCInstLowering.lower(MI, TmpInst);
EmitToStreamer(*OutStreamer, TmpInst);