Vulkan: SPIR-V Gen: Support discard

This is simply done with OpKill. If-else blocks now check if the block is already terminated (through return, discard, continue or break) before adding the branch to merge block. Bug: angleproject:4889 Change-Id: I713286cf38e40f9048486d2914a4355ddbc686ac Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2953369 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com>

Vulkan: SPIR-V Gen: Support discard
99a98963 · Shahbaz Youssefi · Angle LUCI CQ · 1529a30c · 99a98963 · 99a98963
Commit 99a98963 authored Jun 10, 2021 by Shahbaz Youssefi Committed by Angle LUCI CQ Jun 16, 2021
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BuildSPIRV.cpp src/compiler/translator/BuildSPIRV.cpp +8 -5

OutputSPIRV.cpp src/compiler/translator/OutputSPIRV.cpp +2 -2

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--- a/src/compiler/translator/BuildSPIRV.cpp
+++ b/src/compiler/translator/BuildSPIRV.cpp
@@ -1148,12 +1148,15 @@ void SPIRVBuilder::writeBranchConditional(spirv::IdRef conditionValue,
 void SPIRVBuilder::writeBranchConditionalBlockEnd()
 {
-    // Insert a branch to the merge block at the end of each if-else block.
+    if (!isCurrentFunctionBlockTerminated())
-    const spirv::IdRef mergeBlock = getCurrentConditional()->blockIds.back();
+    {
+        // Insert a branch to the merge block at the end of each if-else block, unless the block is
+        // already terminated, such as with a return or discard.
+        const spirv::IdRef mergeBlock = getCurrentConditional()->blockIds.back();
-    ASSERT(!isCurrentFunctionBlockTerminated());
+        spirv::WriteBranch(getSpirvCurrentFunctionBlock(), mergeBlock);
-    spirv::WriteBranch(getSpirvCurrentFunctionBlock(), mergeBlock);
+        terminateCurrentFunctionBlock();
-    terminateCurrentFunctionBlock();
+    }
    // Move on to the next block.
    nextConditionalBlock();

--- a/src/compiler/translator/OutputSPIRV.cpp
+++ b/src/compiler/translator/OutputSPIRV.cpp
@@ -3018,8 +3018,8 @@ bool OutputSPIRVTraverser::visitBranch(Visit visit, TIntermBranch *node)
    switch (node->getFlowOp())
    {
        case EOpKill:
-            // TODO: http://anglebug.com/4889
+            spirv::WriteKill(mBuilder.getSpirvCurrentFunctionBlock());
-            UNIMPLEMENTED();
+            mBuilder.terminateCurrentFunctionBlock();
            break;
        case EOpBreak:
            // TODO: http://anglebug.com/4889