From: Dave Airlie <[email protected]>

We want to use a different intrinsic on newer llvm, so move this
code to a shared area.

Signed-off-by: Dave Airlie <[email protected]>
---
 src/amd/common/ac_llvm_build.c | 24 ++++++++++++++++++++++++
 src/amd/common/ac_llvm_build.h |  4 ++++
 2 files changed, 28 insertions(+)

diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
index 20216a7..180fd24 100644
--- a/src/amd/common/ac_llvm_build.c
+++ b/src/amd/common/ac_llvm_build.c
@@ -763,3 +763,27 @@ ac_emit_sendmsg(struct ac_llvm_context *ctx,
        ac_emit_llvm_intrinsic(ctx, intr_name, ctx->voidt,
                               args, 2, 0);
 }
+
+LLVMValueRef
+ac_emit_imsb(struct ac_llvm_context *ctx,
+            LLVMValueRef arg,
+            LLVMTypeRef dst_type)
+{
+       LLVMValueRef msb = ac_emit_llvm_intrinsic(ctx, "llvm.AMDGPU.flbit.i32",
+                                                 dst_type, &arg, 1,
+                                                 AC_FUNC_ATTR_READNONE);
+
+       /* The HW returns the last bit index from MSB, but NIR/TGSI wants
+        * the index from LSB. Invert it by doing "31 - msb". */
+       msb = LLVMBuildSub(ctx->builder, LLVMConstInt(ctx->i32, 31, false),
+                          msb, "");
+
+       LLVMValueRef all_ones = LLVMConstInt(ctx->i32, -1, true);
+       LLVMValueRef cond = LLVMBuildOr(ctx->builder,
+                                       LLVMBuildICmp(ctx->builder, LLVMIntEQ,
+                                                     arg, 
LLVMConstInt(ctx->i32, 0, 0), ""),
+                                       LLVMBuildICmp(ctx->builder, LLVMIntEQ,
+                                                     arg, all_ones, ""), "");
+
+       return LLVMBuildSelect(ctx->builder, cond, all_ones, msb, "");
+}
diff --git a/src/amd/common/ac_llvm_build.h b/src/amd/common/ac_llvm_build.h
index e88874a..0ff04e4 100644
--- a/src/amd/common/ac_llvm_build.h
+++ b/src/amd/common/ac_llvm_build.h
@@ -182,6 +182,10 @@ void ac_emit_sendmsg(struct ac_llvm_context *ctx,
                     uint32_t msg,
                     LLVMValueRef wave_id);
 
+LLVMValueRef ac_emit_imsb(struct ac_llvm_context *ctx,
+                         LLVMValueRef arg,
+                         LLVMTypeRef dst_type);
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.7.4

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