[Mesa-dev] [PATCH v2 26/41] ac/nir: make ac_find_lsb work on all bit sizes

[Rhys Perry]

v2: don't use ac_get_zero() and ac_int_of_size()

Signed-off-by: Rhys Perry <pendingchao...@gmail.com>
---
 src/amd/common/ac_llvm_build.c | 33 ++++++---------------------------
 1 file changed, 6 insertions(+), 27 deletions(-)

diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
index aa92c55c822..61085db9320 100644
--- a/src/amd/common/ac_llvm_build.c
+++ b/src/amd/common/ac_llvm_build.c
@@ -2474,30 +2474,11 @@ LLVMValueRef ac_find_lsb(struct ac_llvm_context *ctx,
                         LLVMTypeRef dst_type,
                         LLVMValueRef src0)
 {
-       unsigned src0_bitsize = ac_get_elem_bits(ctx, LLVMTypeOf(src0));
-       const char *intrin_name;
-       LLVMTypeRef type;
-       LLVMValueRef zero;
-
-       switch (src0_bitsize) {
-       case 64:
-               intrin_name = "llvm.cttz.i64";
-               type = ctx->i64;
-               zero = ctx->i64_0;
-               break;
-       case 32:
-               intrin_name = "llvm.cttz.i32";
-               type = ctx->i32;
-               zero = ctx->i32_0;
-               break;
-       case 16:
-               intrin_name = "llvm.cttz.i16";
-               type = ctx->i16;
-               zero = ctx->i16_0;
-               break;
-       default:
-               unreachable(!"invalid bitsize");
-       }
+       LLVMTypeRef type = LLVMTypeOf(src0);
+       unsigned src0_bitsize = ac_get_elem_bits(ctx, type);
+       char intrin_name[64];
+       LLVMValueRef zero = LLVMConstInt(type, 0, false);
+       snprintf(intrin_name, sizeof(intrin_name), "llvm.cttz.i%d", 
src0_bitsize);
 
        LLVMValueRef params[2] = {
                src0,
@@ -2518,9 +2499,7 @@ LLVMValueRef ac_find_lsb(struct ac_llvm_context *ctx,
                                              params, 2,
                                              AC_FUNC_ATTR_READNONE);
 
-       if (src0_bitsize == 64) {
-               lsb = LLVMBuildTrunc(ctx->builder, lsb, ctx->i32, "");
-       }
+       lsb = ac_build_ui_cast(ctx, lsb, ctx->i32);
 
        /* TODO: We need an intrinsic to skip this conditional. */
        /* Check for zero: */
-- 
2.20.1

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