[libclc] 71/79: amdgcn, popcount: Workaround broken llvm.ctpop intrinsic on some GCN ASICs

[Andreas Boll]

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commit 034def98aad1f5314a4ec56a07e66f6a8a0cb0db
Author: Jan Vesely <jan.vesely at rutgers.edu>
Date:   Thu Mar 8 18:58:07 2018 +0000

    amdgcn,popcount: Workaround broken llvm.ctpop intrinsic on some GCN ASICs
    
    This is only really needed for VI+ ASICs. However, llvm would cast the value to
    i32 for older asics anyway. The proper fix is in LLVM-7 (r326535).
    Fixes CTS popcount on carrizo.
    
    Reviewer: Aaron Watry <awatry at gmail.com>
    Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
    
    git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@327044 91177308-0d34-0410-b5e6-96231b3b80d8
---
 amdgcn/lib/SOURCES              |  1 +
 amdgcn/lib/integer/popcount.cl  |  6 ++++++
 amdgcn/lib/integer/popcount.inc | 17 +++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/amdgcn/lib/SOURCES b/amdgcn/lib/SOURCES
index 8e14ce2..6a5ce00 100644
--- a/amdgcn/lib/SOURCES
+++ b/amdgcn/lib/SOURCES
@@ -1,4 +1,5 @@
 cl_khr_int64_extended_atomics/minmax_helpers.ll
+integer/popcount.cl
 math/ldexp.cl
 mem_fence/fence.cl
 synchronization/barrier.cl
diff --git a/amdgcn/lib/integer/popcount.cl b/amdgcn/lib/integer/popcount.cl
new file mode 100644
index 0000000..ebd167d
--- /dev/null
+++ b/amdgcn/lib/integer/popcount.cl
@@ -0,0 +1,6 @@
+#include <clc/clc.h>
+#include <utils.h>
+#include <integer/popcount.h>
+
+#define __CLC_BODY "popcount.inc"
+#include <clc/integer/gentype.inc>
diff --git a/amdgcn/lib/integer/popcount.inc b/amdgcn/lib/integer/popcount.inc
new file mode 100644
index 0000000..402ddb7
--- /dev/null
+++ b/amdgcn/lib/integer/popcount.inc
@@ -0,0 +1,17 @@
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE popcount(__CLC_GENTYPE x) {
+/* LLVM-4+ implements i16 ops for VI+ ASICs. However, ctpop implementation
+ * is missing until r326535. Therefore we have to convert sub i32 types to uint
+ * as a workaround. */
+#if __clang_major__ < 7 && __clang_major__ > 3 && __CLC_GENSIZE < 32
+	/* Prevent sign extension on uint conversion */
+	const __CLC_U_GENTYPE y = __CLC_XCONCAT(as_, __CLC_U_GENTYPE)(x);
+	/* Convert to uintX */
+	const __CLC_XCONCAT(uint, __CLC_VECSIZE) z = __CLC_XCONCAT(convert_uint, __CLC_VECSIZE)(y);
+	/* Call popcount on uintX type */
+	const __CLC_XCONCAT(uint, __CLC_VECSIZE) res = __clc_native_popcount(z);
+	/* Convert the result back to gentype. */
+	return __CLC_XCONCAT(convert_, __CLC_GENTYPE)(res);
+#else
+	return __clc_native_popcount(x);
+#endif
+}

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