AMDGPU: Reduce 64-bit lshr by constant to 32-bit

64-bit shifts are very slow on some subtargets.

llvm-svn: 258090

1 files changed, 64 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AMDGPU/shift-i64-opts.ll b/llvm/test/CodeGen/AMDGPU/shift-i64-opts.ll
new file mode 100644
index 00000000000..a74d2e12045
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/shift-i64-opts.ll
@@ -0,0 +1,64 @@
+; RUN: llc -march=amdgcn -mcpu=tahiti < %s | FileCheck -check-prefix=FAST64 -check-prefix=GCN %s
+; RUN: llc -march=amdgcn -mcpu=bonaire < %s | FileCheck -check-prefix=SLOW64 -check-prefix=GCN %s
+
+
+; lshr (i64 x), c: c > 32 => reg_sequence lshr (i32 hi_32(x)), (c - 32), 0
+; GCN-LABEL: {{^}}lshr_i64_35:
+; GCN: buffer_load_dword [[VAL:v[0-9]+]]
+; GCN: v_lshrrev_b32_e32 v[[LO:[0-9]+]], 3, [[VAL]]
+; GCN: v_mov_b32_e32 v[[HI:[0-9]+]], 0{{$}}
+; GCN: buffer_store_dwordx2 v{{\[}}[[LO]]:[[HI]]{{\]}}
+define void @lshr_i64_35(i64 addrspace(1)* %out, i64 addrspace(1)* %in) {
+  %val = load i64, i64 addrspace(1)* %in
+  %shl = lshr i64 %val, 35
+  store i64 %shl, i64 addrspace(1)* %out
+  ret void
+}
+
+; GCN-LABEL: {{^}}lshr_i64_63:
+; GCN: buffer_load_dword [[VAL:v[0-9]+]]
+; GCN: v_lshrrev_b32_e32 v[[LO:[0-9]+]], 31, [[VAL]]
+; GCN: v_mov_b32_e32 v[[HI:[0-9]+]], 0{{$}}
+; GCN: buffer_store_dwordx2 v{{\[}}[[LO]]:[[HI]]{{\]}}
+define void @lshr_i64_63(i64 addrspace(1)* %out, i64 addrspace(1)* %in) {
+  %val = load i64, i64 addrspace(1)* %in
+  %shl = lshr i64 %val, 63
+  store i64 %shl, i64 addrspace(1)* %out
+  ret void
+}
+
+; GCN-LABEL: {{^}}lshr_i64_33:
+; GCN: buffer_load_dword [[VAL:v[0-9]+]]
+; GCN: v_lshrrev_b32_e32 v[[LO:[0-9]+]], 1, [[VAL]]
+; GCN: v_mov_b32_e32 v[[HI:[0-9]+]], 0{{$}}
+; GCN: buffer_store_dwordx2 v{{\[}}[[LO]]:[[HI]]{{\]}}
+define void @lshr_i64_33(i64 addrspace(1)* %out, i64 addrspace(1)* %in) {
+  %val = load i64, i64 addrspace(1)* %in
+  %shl = lshr i64 %val, 33
+  store i64 %shl, i64 addrspace(1)* %out
+  ret void
+}
+
+; GCN-LABEL: {{^}}lshr_i64_32:
+; GCN: buffer_load_dword v[[LO:[0-9]+]]
+; GCN: v_mov_b32_e32 v[[HI:[0-9]+]], 0{{$}}
+; GCN: buffer_store_dwordx2 v{{\[}}[[LO]]:[[HI]]{{\]}}
+define void @lshr_i64_32(i64 addrspace(1)* %out, i64 addrspace(1)* %in) {
+  %val = load i64, i64 addrspace(1)* %in
+  %shl = lshr i64 %val, 32
+  store i64 %shl, i64 addrspace(1)* %out
+  ret void
+}
+
+; GCN-LABEL: {{^}}lshr_and_i64_35:
+; XGCN: buffer_load_dword [[VAL:v[0-9]+]]
+; XGCN: v_lshlrev_b32_e32 v[[LO:[0-9]+]], 3, [[VAL]]
+; XGCN: v_mov_b32_e32 v[[HI:[0-9]+]], 0{{$}}
+; XGCN: buffer_store_dwordx2 v{{\[}}[[LO]]:[[HI]]{{\]}}
+define void @lshr_and_i64_35(i64 addrspace(1)* %out, i64 addrspace(1)* %in) {
+  %val = load i64, i64 addrspace(1)* %in
+  %and = and i64 %val, 2147483647 ; 0x7fffffff
+  %shl = lshr i64 %and, 35
+  store i64 %shl, i64 addrspace(1)* %out
+  ret void
+}