[AMDGPU] Fix clamp bit DAG operand

Summary:
- Should use `targetconstant` instead of `constant` operand for clamp
  bit, which is expected as an immediate operand. Under certain
  conditions, such as a common `i1 false` constant is used in other
  place and selected before the instruction with clamp bit, register
  operand may be added instead of immediate one. Use `targetcosntant` to
  enforce that.

Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59608

llvm-svn: 356608

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AMDGPU/uaddo.ll b/llvm/test/CodeGen/AMDGPU/uaddo.ll
index cd9ea4d3437..e23a8530b8a 100644
--- a/llvm/test/CodeGen/AMDGPU/uaddo.ll
+++ b/llvm/test/CodeGen/AMDGPU/uaddo.ll
@@ -170,6 +170,28 @@ define amdgpu_kernel void @v_uaddo_v2i32(<2 x i32> addrspace(1)* %out, <2 x i32>
   ret void
 }
 
+; FUNC-LABEL: {{^}}s_uaddo_clamp_bit:
+; GCN: v_add_{{i|u|co_u}}32_e32
+; GCN: s_endpgm
+define amdgpu_kernel void @s_uaddo_clamp_bit(i32 addrspace(1)* %out, i1 addrspace(1)* %carryout, i32 %a, i32 %b) #0 {
+entry:
+  %uadd = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
+  %val = extractvalue { i32, i1 } %uadd, 0
+  %carry = extractvalue { i32, i1 } %uadd, 1
+  %c2 = icmp eq i1 %carry, false
+  %cc = icmp eq i32 %a, %b
+  br i1 %cc, label %exit, label %if
+
+if:
+  br label %exit
+
+exit:
+  %cout = phi i1 [false, %entry], [%c2, %if]
+  store i32 %val, i32 addrspace(1)* %out, align 4
+  store i1 %cout, i1 addrspace(1)* %carryout
+  ret void
+}
+
 
 declare i32 @llvm.amdgcn.workitem.id.x() #1
 declare { i16, i1 } @llvm.uadd.with.overflow.i16(i16, i16) #1