[llvm] [CGP] Consider arguments and ret values in `dupRetToEnableTailCallOpts` (PR #76613)

[Antonio Frighetto via llvm-commits]

================
@@ -184,3 +184,126 @@ return:
   %retval = phi ptr [ %ptr, %if.then ], [ %obj, %entry ]
   ret ptr %retval
 }
+
+define ptr @memset_tailc(ptr %ret_val, i64 %sz) {
+; CHECK-LABEL: memset_tailc:
+; CHECK:  ## %bb.0: ## %entry
+; CHECK:    testq %rdi, %rdi
+; CHECK:    je LBB4_1
+; CHECK:  ## %bb.2: ## %if.then
+; CHECK:    movq %rsi, %rdx
+; CHECK:    xorl %esi, %esi
+; CHECK:    jmp _memset ## TAILCALL
+; CHECK:  LBB4_1: ## %return
+; CHECK:    movq %rdi, %rax
+; CHECK:    retq
+entry:
+  %cmp = icmp eq ptr %ret_val, null
+  br i1 %cmp, label %return, label %if.then
+
+if.then:
+  tail call void @llvm.memset.p0.i64(ptr nonnull align 1 %ret_val, i8 0, i64 %sz, i1 false)
+  br label %return
+
+return:
+  ret ptr %ret_val
+}
+
+define ptr @memcpy_tailc(ptr %ret_val, i64 %sz, ptr %src) {
+; CHECK-LABEL: memcpy_tailc:
+; CHECK:  ## %bb.0: ## %entry
+; CHECK:    testq %rsi, %rsi
+; CHECK:    je LBB5_1
+; CHECK:  ## %bb.2: ## %if.then
+; CHECK:    movq %rsi, %rax
+; CHECK:    movq %rdx, %rsi
+; CHECK:    movq %rax, %rdx
+; CHECK:    jmp _memcpy ## TAILCALL
+; CHECK:  LBB5_1: ## %return
+; CHECK:    movq %rdx, %rax
+; CHECK:    retq
+entry:
+  %cmp = icmp eq i64 %sz, 0
+  br i1 %cmp, label %return, label %if.then
+
+if.then:
+  tail call void @llvm.memcpy.p0.p0.i64(ptr align 1 %ret_val, ptr align 1 %src, i64 %sz, i1 false)
+  br label %return
+
+return:
+  %phi = phi ptr [ %ret_val, %if.then ], [ %src, %entry ]
+  ret ptr %phi
+}
+
+define ptr @strcpy_tailc(i64 %0, ptr %src) {
----------------
antoniofrighetto wrote:

Added https://clang.godbolt.org/z/a3rns4883, thanks.

https://github.com/llvm/llvm-project/pull/76613