From b8ade05df10a2774d3da5ef1fb2c7479ff48989a Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Wed, 26 Jul 2023 12:23:53 -0700
Subject: Fix scalar swizzle causes invalid glsl output.  (#3028)

* Fix -fvk-u-shift not applying to RWStructuredBuffer on glsl output.

* Add `transpose` to `ObjectToWorld4x3`.

* Fix scalar swizzle causes invalid glsl output.

Fixes #3026.

---------

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-ir-peephole.cpp             | 25 +++++++++++++++++++++++++
 tests/bugs/glsl-int-swizzle.slang              | 14 ++++++++++++++
 tests/bugs/glsl-int-swizzle.slang.expected.txt |  4 ++++
 3 files changed, 43 insertions(+)
 create mode 100644 tests/bugs/glsl-int-swizzle.slang
 create mode 100644 tests/bugs/glsl-int-swizzle.slang.expected.txt

diff --git a/source/slang/slang-ir-peephole.cpp b/source/slang/slang-ir-peephole.cpp
index ac026b563..600361b2f 100644
--- a/source/slang/slang-ir-peephole.cpp
+++ b/source/slang/slang-ir-peephole.cpp
@@ -759,6 +759,31 @@ struct PeepholeContext : InstPassBase
             break;
         case kIROp_swizzle:
             {
+                // If we see a swizzle(scalar), we replace it with makeVectorFromScalar.
+                if (as<IRBasicType>(inst->getOperand(0)->getDataType()))
+                {
+                    auto vectorType = as<IRVectorType>(inst->getDataType());
+                    IRIntegerValue vectorSize = 1;
+                    if (vectorType)
+                    {
+                        auto sizeLit = as<IRIntLit>(vectorType->getElementCount());
+                        if (!sizeLit)
+                            vectorSize = 0;
+                        vectorSize = sizeLit->getValue();
+                    }
+                    if (vectorSize == 1)
+                    {
+                        inst->replaceUsesWith(inst->getOperand(0));
+                        maybeRemoveOldInst(inst);
+                        break;
+                    }
+                    IRBuilder builder(module);
+                    builder.setInsertBefore(inst);
+                    auto newInst = builder.emitMakeVectorFromScalar(vectorType, inst->getOperand(0));
+                    inst->replaceUsesWith(newInst);
+                    maybeRemoveOldInst(inst);
+                    break;
+                }
                 // If we see a swizzle(makeVector) then we can replace it with the values from makeVector.
                 auto makeVector = inst->getOperand(0);
                 if (makeVector->getOp() != kIROp_MakeVector)
diff --git a/tests/bugs/glsl-int-swizzle.slang b/tests/bugs/glsl-int-swizzle.slang
new file mode 100644
index 000000000..6dccf69f0
--- /dev/null
+++ b/tests/bugs/glsl-int-swizzle.slang
@@ -0,0 +1,14 @@
+// glsl-int-swizzle.slang
+
+//TEST(compute):COMPARE_COMPUTE:-vk -shaderobj
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name gBuffer
+RWStructuredBuffer<int> gBuffer;
+
+int getX(int4 v) { return v.x; }
+
+[numthreads(4,1,1)]
+void computeMain(uint3 tid : SV_DispatchThreadID)
+{
+    gBuffer[tid.x] = getX((1).xxxx);
+}
diff --git a/tests/bugs/glsl-int-swizzle.slang.expected.txt b/tests/bugs/glsl-int-swizzle.slang.expected.txt
new file mode 100644
index 000000000..98fb6a686
--- /dev/null
+++ b/tests/bugs/glsl-int-swizzle.slang.expected.txt
@@ -0,0 +1,4 @@
+1
+1
+1
+1
-- 
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