diff options
Diffstat (limited to 'source/slang/slang-emit.cpp')
| -rw-r--r-- | source/slang/slang-emit.cpp | 68 |
1 files changed, 42 insertions, 26 deletions
diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp index 1b94c588b..0539f9d1d 100644 --- a/source/slang/slang-emit.cpp +++ b/source/slang/slang-emit.cpp @@ -10,6 +10,7 @@ #include "slang-ir-collect-global-uniforms.h" #include "slang-ir-dce.h" #include "slang-ir-dll-import.h" +#include "slang-ir-eliminate-phis.h" #include "slang-ir-entry-point-uniforms.h" #include "slang-ir-entry-point-raw-ptr-params.h" #include "slang-ir-explicit-global-context.h" @@ -731,39 +732,54 @@ Result linkAndOptimizeIR( lowerBitCast(targetRequest, irModule); simplifyIR(irModule); - // TODO(JS): We probably want to add a pass that moves phi-node temporaries to - // IR. - // - // Currently these are added as part of emit in - // emitPhiVarAssignments and emitPhiVarDecls - // - // A possible mechanism might be: - // 1) Find all of the parameters passed between blocks - // 2) Make a variable for each one of them - // This could be at the scope for the function, or more ideally a scope that is 'most appropriate' for how the parameter is passed - // ie the closest scope such that the variable is in scope across the branch. - // 3) Replace all uses of the parameters passed into a block (except the entry block), with the temporary - // 3a) Remove the parameters from the start of a block (other than the entry block) - // 4) For all of the branches in a function - // 4a) For each parameter passed in the branch, assign to the temporary - // 4b) Replace the branch with a branch that has no parameters // - // This should lead to an equivalent function, where the parameter passing between blocks is removed, and all the temporaries - // are explicit in the output. - // - // I guess there could be a desire to combine the liveness tracking into this pass, because once a phi-temporary has been moved - // we have lost(?) information about liveness. That could potentially be recovered, but for the phi-temporaries, their - // initial liveness is trivial, it's when the assignment takes place, at the branch point. - // - // If all the temporaries were marked as such, then this would be fairly trivial to recreate. - - // TODO(JS): Without a pass to make all variables (including phi ones), the liveness tracking can't track everything + // Downstream targets may benefit from having live-range information for + // local variables, and our IR currently encodes a reasonably good version + // of that information. At this point we will insert live-range markers + // for local variables, on when such markers are requested. + // + // After this point in optimization, any passes that introduce new + // temporary variables into the IR module should take responsibility for + // producing their own live-range information. + // if (codeGenContext->shouldTrackLiveness()) { addLivenessTrackingToModule(irModule); dumpIRIfEnabled(codeGenContext, irModule, "LIVENESS"); + } + + // As a late step, we need to take the SSA-form IR and move things *out* + // of SSA form, by eliminating all "phi nodes" (block parameters) and + // introducing explicit temporaries instead. Doing this at the IR level + // means that subsequent emit logic doesn't need to contend with the + // complexities of blocks with parameters. + // + eliminatePhis(codeGenContext, irModule); +#if 0 + dumpIRIfEnabled(codeGenContext, irModule, "PHIS ELIMINATED"); +#endif + // TODO: We need to insert the logic that fixes variable scoping issues + // here (rather than doing it very late in the emit process), because + // otherwise the `applyGLSLLiveness()` operation below wouldn't be + // able to see the live-range information that pass would need to add. + // For now we are avoiding that problem by simply *not* emitting live-range + // information when we fix variable scoping later on. + + // Depending on the target, certain things that were represented as + // single IR instructions will need to be emitted with the help of + // function declaratons in output high-level code. + // + // One example of this is the live-range information, which needs + // to be output to GLSL code that uses a glslang extension for + // supporting function declarations that map directly to SPIR-V opcodes. + // + // We execute a pass here to transform any live-range instructions + // in the module into function calls, for the targets that require it. + // + if (codeGenContext->shouldTrackLiveness()) + { if (isKhronosTarget(targetRequest)) { applyGLSLLiveness(irModule); |